6. Hierarchy of Classification :

7. Monera: They have unicellular, Prokaryotic organisms (do not have defined nucleus or organelles). The cell wall may or may not present. The mode of nutrition is autotrophic (synthesizing food on their own) (or)heterotrophic (getting food from environment). Ex. Bacteria, Anabaena.
8. Protista: They have unicellular eukaryotic organisms (do have well defined nucleus or organelles). The body is covered by cilia, flagella for locomotion. The mode of nutrition is autotrophicorheterotrophic. Ex. Diatoms, protozoans.(Please refer to Fig. 7.2 NCERT Book Page-84)
9. Fungi: These are multi-cellular eukaryotic organisms with cell wall, made up of Chitin. They do not perform Photosynthesis (heterotrophic), Saprophytic (derive nutrition from decaying material). Ex. Aspergillus, Penicillium, Mushroom, Rhizopus. The fungi living with algae forms Lichen (Symbiotic Association) .
10. Plantae: These are multi-cellular eukaryotic organisms with cell wall, made up of Cellulose. Able to perform photosynthesis (autotrophic). Ex. Rice, wheat.

11. Animalia: These are multi-cellular eukaryotic organisms without cell wall. They are not able to perform photosynthesis (heterotrophic).

Ex Human beings, Peacock.

DETAILS OF KINGDOM PLANTAE

1. The kingdom Plantae is further classified as Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, Angiosperms .

2.Thallophyta: The plants do not have well defined body design, commonly called as” Algae”, mostly aquatic. Ex. Spirogyra, Ulothrix. 

3.Bryophyta: These are commonly called as the “Amphibians of Kingdom”. The plant body is differentiated into roots like, stem like and leaf like structures. No specialized tissues for the conduction of water and food.Ex. Marchantia, Funaria.

4.Pteridophyta: These are commonly called as the “First vascular land plants ”. The plant body is differentiated into root, stem and leaf. Specialized tissues for the conduction of water and food are developed in these plants. The reproductive organs are inconspicuous. Ex. Marsilea, Fern.

Special Note: The reproductive organs are inconspicuous in Thallophyta, Bryophyta, Pteridophyta are can’t develop seeds. They are together called as” Cryptogamae (Non- Flowering Plants)”. The plants with well differentiated reproductive organs and that ultimately make seeds are called” Phanerogams (Flowering Plants)”. This group is further classified Gymnosperms (Bear naked Seeds) &Angiosperms (Bears seeds inside Fruit).

5. Gymnosperms: These are commonly called as “Naked seed bearing plants”. They areusually perennial, evergreen and woody. Ex. Pinus, Cycas

6. Angiosperms: These are commonly called as “Enclosed seed bearing plants”. Plants with seeds having a single cotyledon are called as” Monocotyledons or Monocots”. Plants with seeds having two cotyledons are called as “Dicots”. Ex. Ipomoea, Paphiopedium.

These are Eukaryote, multicultural and hetero-tropic.

They are further classified as Non- Chordates( Porifera, Coelenterata, Platyhelminthes , Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata) and Chordates { Protochordata, Vertebrata ( Pisces, Amphibians, Reptilia, Aves, Mammalia)} .

I.Non- Chordates

1. Porifera: The word Porifera” means organisms with holes”. The canal system helps in circulating water, food, oxygen. They are non-motile with cellular level of organization and mainly marine organisms with hard outer coat called as Skeleton. They are commonly called as Sponges. Ex. Spongilla, Sycon

2. Coelenterata: The wordCoelenterata” means organisms with body cavity calledCoelenteron” . They are radially symmetrical, Diploblastic ( two layers of cells), commonly called as Cnidarians ( Stinging cells for protection are present in the body). Ex. Hydra, Sea Anemone

3. Platyhelminthes: The word Platyhelminthes means organisms with flatworms ( dorsocentrally flattened)”.They are bilaterally symmetrical Triploblastic ( three layers ofcells ), either free-living or parasitic. No true Coelom is present - Acoelomates. Ex. Planaria( Free living) , Tape worm( Parasitic)

4. Nematoda: The word Nematoda “means organisms with roundworms”. They are bilaterally symmetrical Triploblastic ( three layers of cells ), familiar with parasitic worms. The false Coelom is called as Pseudocoelome. Ex. Ascaris, Wuchereria (Filarial worm causes elephantiasis)

The word Annelida “ means organisms with metameric-segmented”. They are bilaterally symmetrical Triploblastic(three layers of cells) with closed circulatory system, familiar with earth worms. The Coelom is called as true Coelom. Ex. Neris, Earth worm, Leech

6. Arthropoda: The word Arthropoda “means organisms with jointed legs” They are bilaterally symmetrical Triploblastic(three layers of cells ), familiar with cockroaches. The Coelom is blood filled called as Haemo Coelom. Ex. Prawn, Scorpion, Housefly

7.Mollusca: The word Mollusca “means organisms with soft body” They are bilaterally symmetrical, Triploblastic(three layers of cells), familiar with Octopus, Pila. Foot is for moving, kidney like organ for excretion, with open circulatory system. Ex. Unio, chiton

8. Echinodermata: The word Echinodermata “means organisms with spiny skinned”. Exoskeleton is with calcium carbonate. They are radially symmetrical Triploblastic ( three layers of cells ) with coelomic cavity, familiar with Star fish. They are exclusively free-living marine animals. Ex. Sea Cucumber, Feather Star

II.Chordates: They are further classified as two major groups such as Protochordata& Vertebrata

(A).Protochordata: Notochord present in at least larval forms, but very rudimentary. It is a rod like supporting structure, runs along with nervous tissue from the gut of animal. They
are bilaterally symmetrical, triploblastc(three layers of cells) with a Coelom, familiar with Amphioxus. Ex. Balanoglossus

(B).Vertebrata: Notochord is replaced by vertebral column and internal skeleton. They are bilaterally symmetrical, triploblastic, coelomic and segmented having paired gill pouches. Vertebrates are grouped into five classes.

1. Pisces: These are commonly called as “fishes”, exclusively aquatic. Body is streamlined and a tail for locomotion. Gills for respiration, heart is two chambered, cold blooded, skin is covered with scales, plates. They are cold-blooded animals. Skeleton of bone ( Rohu) / cartilage( Shark). They lay eggs. Ex. Lion Fish, Dog Fish(Please refer Fig. 7.21, NCERT Text Book Page- 92).

2. Amphibians: These are commonly called as “Amphibians” because they can live on land and in water”. Body is streamlined and a webbed foot/ foot for locomotion. Gills or lungs or skin for respiration, heart is three chambered, cold blooded, skin is lack of scales, plates. They are cold-blooded animals. They lay eggs. Ex. Rana, Hyla

3. Reptilia: These are commonly called as “Reptilians”. A lung for respiration, heart is three chambered (Crocodile heart is four chambered), skin have scales. They are cold-blooded animals. They lay eggs. Ex. Snakes, Turtles

4. Aves :These are commonly called as “Birds”. A lung for respiration, heart is four chambered, fore limbs are modified for flight, skin has feathers. They are warm-blooded animals. They lay eggs. Ex. Ostrich (Flightless Bird), Pigeon, Sparrow

5. Mammalia: These are commonly called as “animals with mammary glands for producing milk to nourish their young ones”. A lung for respiration, heart is four chambered, skin has hairs, sweat or oil glands. They are warm-blooded animals. They lay eggs (Platypus, Echidna), give birth to young ones poorly developed (Kangaroo) & give birth to developed young ones (Human beings). Ex. Lion, Whale, Bat

DETAILS OF NOMENCLATURE

NOMENCLATURE: The system of scientific naming or nomenclature was introduced by Carolus Linnaeus. It is unique to identify in the world. We limit ourselves to writing the names of the Genus and Species of that particular organism. The world over, it has been agreed that both these names will be used in Latin forms.When printed is given in italics and when written by hand, the Genus and Species name have to be underlined separately.

Ex. Ostrich (Common name): Struthiocamelus(scientific name with two parts namely the Genus and Species).

QUESTION BANK

1. What is the book written by Charles Darwin?...................... (The Origin of Species)
2. Who proposed the five kingdoms such as, Monera, Protista, Fungi, Plantae and Animalia? (Whittaker)
3.Monera members areunicellular, Prokaryotic organisms, mention TRUE/ FALSE ….. (TRUE)
4. The Diatoms belongs to the kingdom................. ( Protista)
5. TheAnabaena belongs to the kingdom …………………(Monera)
6……………………. are commonly called as the“Amphibians of Plant Kingdom”.( Bryophyta)
7. The warm-blooded animals with fore limbs modified for flight, skin has feathers are called as………………….. (Aves/Birds)
8. Write the four salient features of Reptiles.
9.Compare the Pisces and Amphibians.
77
10..Write the five salient features of Mammalia, give two examples.

1. Questions 1-5 (1 Mark each)

2. Questions 6-10 ( 2 Mark each)

3. Questions 11-15 (3Mark each)

4.. Questions 16-17 (5Mark each)

Q.1 Anabaena is member of the Phylum…………………………………
Q.2 Aspergillum is a member of the Phylum……………………………..
Q.3 Define the term Autotrophic mode of nutrition………………….
Q.4 The fungus living with algae is called as ……………………………..
Q.5 Name the scientist who has divided the Monera into two sub-groups…………………..
Q.6 Draw and label Paramecium.
Q.7 Distinguish the meaning of terms Gymnosperms and Angiosperms.
Q.8 What is Pseudocoelome? Give one example of it.
Q.9 What is Haemocoelome? Give one example of it.
Q.10 Write two salient features of mammalian group.
Q.11 What is the basis of nomenclature of organisms, give the scientific name of Ostrich.
Q.12 Give three salient features of Amphibia.
Q.13 Mention three features of Chordates.
Q.14. Draw and label Balanoglossus.
Q.15 Give two salient features of Aves and mention one example of a flightless bird.
Q.16 Write about the Hierarchy of Classification- Groups and mention basic unit of
classification.

Q.17 Give the salient features of Bryophytes and draw the diagram of Funaria.

(Please refer to Fig. 6.7, NCERT Book Page-73).

6. Animal tissues: Sub divided as epithelial tissue, connective tissue, muscular tissue and nervous tissue.

i. Epithelial tissue: It is a protective covering forming a continuous sheet. Simple epithelium is the one which is extremely thin in one layer, whereas stratified epithelium are arranged in pattern of layers.

Depending on shape and function they are classified as:

a) Squamous epithelium in the lining of mouth and esophagus.

b) Cuboidal epithelium in the lining of kidney tubules and salivary glands.

c) Columnar epithelium in the intestine &Columnar epithelium with cilia in the lining of respiratory tract.

d) Glandular epithelium in the Glands aids in a special function as gland cells, which can secrete at the epithelial surface.

(Please refer to Fig. 6.9, NCERT Book Page-75).

ii) Connective Tissue: Five Types, such as;

a) Blood: The Blood is a fluid connective tissue. Blood plasma has RBCs (Red Blood Cells) WBCs (White Blood Cells) and platelets. Blood plasma contains proteins, salts and hormones. Blood flows and transports gases, digested food, hormones and waste materials.

b) Bone: The bone is a connective tissue with hard matrix, composed of calcium and phosphorus. A bone is connected by another bone with another connective tissue called ligaments. A bone is connected by muscle with another connective tissue called tendon.

c) Cartilage: The cartilage is a connective tissue with solid matrix composed of proteins and sugars. It is commonly seen in nose, ear, trachea, and larynx.

d) Areolar Connective Tissue: It is found between the skin and muscles, around the blood vessels. It supports internal organs and aids in repair of tissues.

e))Adipose Connective Tissue: It is filled with fat globules for the storage of fat. It acts as insulator.

(Please refer to Fig. 6.10, NCERT Book Page-76).

Muscular tissues: They have special contractile proteins responsible for movements. Three types, such as;

Striated muscles/skeletal muscles/voluntary muscles :

They are cylindrical, un-branched and multinucleated.They have dark bands and light bands.

Unstriated muscles/smooth muscles/involuntary muscles:

They are commonly called as Smooth muscles, having no striations (dark bands/ light bands are absent). Commonly found alimentary canal, uterus, Iris of an Eye. They are spindle shaped. Involuntary in nature

Cardiac Muscles: They are commonly called as Heart muscles, cylindrical, 68 branched and uni-nucleate. Involuntary in nature.

(Please refer to Fig. 6.11, NCERT Book Page-77).

Nervous Tissue: The tissue responds to stimuli. The brain, spinal cord and nerves are composed of nervous tissue or neurons. A neuron consists of Cell Body, cytoplasm, Nucleus, Dendrite, Axon, nerve ending. The neuron impulse allow us to move our muscles when we want to respond to stimuli. (Please refer to Fig. 6.12, NCERT Book Page-78).

QUESTION BANK

1. Define the term tissue……………. ( A group of cells forms tissue)

2. What is Histology? ( Study of different tissues)

3. How many types of meristems are present in plants? (3 : Apical meristems, Lateral meristem, Intercalary meristem )

4. Name the Parenchyma with chlorophyll which performs photosynthesis………………… (chlorenchyma)

5. Which plant tissue makes the plant hard and stiff and thickened due to lignin with no intercellular spaces …………………….(Sclerenchyma)

6. Give the details of epidermal tissue in Plants. (For protection and exchange of gases. Guard cells kidney shaped in dicots, dumb bell shaped in monocots to guard the stomata. The epidermal tissues of roots aid in absorption of water and minerals.)

7. Which elements constitute the Phloem? (Sieve tubes, companion cells, phloem parenchyma, and phloem fibers.)

8. Distinguish between ligament and tendon (A bone to bone connective tissue called ligament. A bone to muscle connective tissue called tendon.)

9. Name the three muscular tissues in the animals……..(Striated muscles ,Un- Striated muscles, Cardiac Muscles)

10. Draw the neuron and label it (Please refer to Fig. 6.12, NCERT Book Page-78).

QUESTION PAPER: FORMATIVE ASSESSMENT – I (For Practice)
 

Q.1 What is a group of cells that are similar in structure and work called?

Q.2 Which is the hardest connective tissue?

Q.3 What is the name of Blood matrix?

Q.4 By what process permanent tissues are formed?

Q.5 Two bones are connected with ligaments. Mention True/ False…………….

Q.6 What are the two main types of tissues found in plants? Q.7 Draw the structure of Stomata and label it.

Q.8 Write the main functions of parenchyma

Q.9 What are the fluid connective tissues?

Q.10 What is the difference between voluntary and involuntary muscles?

Q.11 Write a short notes on Cardiac muscles.

Q.12 Draw a labeled diagram of areolar tissue.

Q.13 Mention the three elements of Xylem tissue.

Q.14. Write a short notes on Glandular Epithelium.

Q.15. Write three significant points about Sclerenchyma

Q.16 With the help of suitable diagram, describe the Phloem.

Q.17 Draw and label the Nerve Cell.Explain in brief.

2. The cell is a Latin word for “a little room”.

3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) resembled the structure of a honeycomb. The use of the word “Cell” to describe these units is used till this day in Biology as” Cell Biology”.

4. The Compound Microscope consist eye piece,objective lens and condenser to observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)

5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( father of microbiology)

6. The scientist Robert Brown discovered the nucleus in the cell.

7. The cell theory states that all the plants and animals are composed of cells, it was proposed by Schleiden and Schwann.

8. The cell theory was further expanded by Virchow by suggesting that “all cells arise from the pre-existing cells”.

9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm etc. Each kind of cell performs specific function. 59

10. A single cell may constitute a whole organism as in Amoeba, Chlamydomonas, Paramecium and Bacteria; these are called as unicellular organisms. Whereas in multi-cellular organisms (Human beings) division of labor is seen.

11. The feature in almost every cell is same: Plasma membrane, nucleus and cytoplasm.

12. Plasma membrane: It is the outermost covering of the cell.
- It is called as selective permeable membrane (because it prevents movement of some materials).
- It helps in diffusion and osmosis
- Diffusion: movement of substance from high concentration to low concentration.
Eg; exchange of carbon dioxide or oxygen with external environment.
 

osmosis: it is the passage of water from the region of high water concentration to a region of low water concentration through a selective permeable membrane.
 

a) The cell gains water, if the medium surrounding the cell has a higher water concentration (Hypotonic solution) than the cell.
b) The cell maintains the same water concentration as the cell (Isotonic solution), water crosses the cell membrane in both directions.
c)The cell loses water, if the medium has lower water concentration (Hypertonic solution) than the cell.

Note - The cell drinking is endosmosis;

      - omission of water is called ex-osmosis.

13. The cell engulfs food is called endocytosis and ejects solid is called exocytosis. Amoeba acquires food through endocytosis and excretion of solid is called exocytosis.

14. The cell wall is a rigid outer covering composed of cellulose. It provides structural strength to plant cells. When a living cell loses water, there is shrinkage of contents of a cell away from the cell wall. This phenomenon is called as plasmolysis. The cell walls permit the cells of plants, fungi and bacteria to withstand very dilute (Hypotonic) external media without bursting.

15. The Nucleus: It is a dark colored, spherical or oval, dot-like structure near the center of a cell called Nucleus. The nucleus plays a central role in cellular activities/ reproduction. The chromatin material gets organized into chromosomes. The chromosomes contain information for inheritance of features from parents to next generations in the form of DNA( Deoxyribo Nucleic Acid ) and protein molecules. The functional segments of DNA are called genes.

16. In some organisms like Bacteria nucleus is not covered by nuclear membrane. Hence it is called as prokaryote. (Pro= primitive; karyote = karyon = nucleus.) The organisms with cells having a nuclear membrane are called eukaryotes. 17. Differences between prokaryotes and eukaryotes( Please refer to Fig. 5.4: Prokaryotic cell NCERT Book Page-62)

18. Cell organelles: Every cell has fluid matrix (other than nucleus) is called cytoplasm. The nucleus and cytoplasm is together called as protoplasm. The protoplasm term was coined by Purkinje. It has important cell organelles: Endoplasmic Reticulum (ER), Golgi apparatus, Lysosomes, Mitochondria, Plastids, and vacuoles.

19. Endoplasmic Reticulum (ER): It is a large network of membrane –bound tubules and vesicles.

- There are two types of Endoplasmic Reticulum
- Rough Endoplasmic Reticulum (RER) (It looks rough because Ribosomes are attached to its surface. They are the sites of protein synthesis).
- Smooth Endoplasmic Reticulum (SER) (It looks smooth because Ribosomes are not attached to its surface. They are the sites of fat molecules synthesis).

1. SER ; help in the functioning of enzymes and hormones to carryout biochemical activities.
2. SER detoxifies many poisons and drugs from the cell.
2. ER serves as channel for the transport of material between various regions of the cytoplasm and the nucleus.
3. Proteins and fat molecules produced by ER helps in membrane biogenesis.

20. Golgi apparatus: It was first described by a scientist Camillo Golgi. It is a system of membrane bound vesicles called cisterns. It functions include the storage, modification and package of cell products. The complex sugars are made from simple sugars in the Golgi apparatus. It is also involved in the formation of lysosomes.

21. Lysosomes: They contain membrane-bound sacs with powerful digestive enzymes (enzymes are made by RER) to digest the worn-out cell organelles. When the cell gets damaged, lysosomes may burst and the enzymes digest their own cell, hence called as “Suicidal bags of a cell”. It is a waste disposal system of the cell.

22. Mitochondria: It is covered by a double membrane. Outer membrane is very porous and the inner membrane is deeply folded. These folds create a large surface area for ATP (Adenosine Triphosphate) molecule synthesis. ATP is the energy currency of a cell; hence the Mitochondria are called as Power House of a Cell. Mitochondria have their own DNA and Ribosomes; therefore they can make their own proteins.

23. Plastids: They are present only in plant cells. They are two types.

1. Chromoplasts (Colored Plastids: Chloroplasts – Green pigmented and useful in Photosynthesis and also contains various other pigments like yellow or orange)

2. Leucoplasts (White or colorless plastids; stores materials such as oils, proteins, fats etc. ) Plastids are also covered by a double membrane. The matrix is called Stroma, seat for enzymatic actions. Plastids have their own DNA and Ribosomes; therefore they can make their own proteins.

24. Vacuoles: Storage sacs for solid or liquid contents. They are small in size in animals while plants have large, may occupy 50-90 % of the cell volume. Helps to provide turgidity and rigidity to the cell. Many substances like amino acids, sugars, organic acids and proteins are stored in vacuoles. In Amoeba food vacuole is specialized to play an important role. 25. Cell: It is the fundamental structural unit of living organisms, helps in respiration, obtaining nutrition and clearing waste material or forming a new protein. Differences between Plant cell and Animal Cell

(Please refer to Fig. 5.5 Animal cell & 5.6: Plant cell NCERT Book Page-63&64)

QUESTION BANK

1. All the living organisms are composed of fundamental unit called as…………. ( Cell)

2. Who discovered the nucleus in the cell……………………….( Robert Brown)

3. Who saw the free living cells for the first time……………..( Leeuwenhoek)

4. Name two unicellular organisms …………….. ………………..( Amoeba, Chlamydomonas,)

5. Write two differences between prokaryotes and eukaryotes……………..( Nuclear region/ Chromosome)

6. What are the two types of ERs ……. ( RER/ SER)

7. What are the functions of Golgi Bodies? (It includes the storage, modification and package of cell products. The complex sugars are made from simple sugars in the Golgi apparatus).

8. What are the types of plastids (Chromoplasts& Leucoplasts)

9. Which are the substances stored in vacuoles? (Substances like amino acids, sugars, organic acids and proteins are stored in vacuoles)

10. Draw and label Animal cell & Plant cell( Ref NCERT Book Page-63&64)

QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

Q.1 What is ATP, expand the term ……………………………………..

Q.2 Cellulose is a Fat (Mention,True/False)……………………………

Q.3 Which cell organelle is synthesizing the enzymes for the Golgi Apparatus……………

Q.4 The flexibility of the cell membrane to engulf food and other material is called Endocytosis (Mention, True /False)………………………………………

Q.5 What is the main function of Leucoplasts? Q.6 Draw the structure of Ovum.

Q.7 Why the Plasma membrane is called as Selective Permeable Membrane?

Q.8 Describe what is an isotonic solution

Q.9 What is Plasmolysis?

Q.10 Write any two parts of a Compound microscope.

Q.11 Distinguish between Prokaryotic and Eukaryotic Cell.

Q.12 Write about the three properties of Cytoplasm.

Q.13 What is the significance of Vacuoles

Q.14 Write a short notes on Mitochondria.

Q.15 Explain the concept of diffusion.

Q.16 Draw the structure of a plant Cell and label it.

Q.17 Write the differences between a plant and animal cell.

• More than 2400 years ago, he named the smallest piece of matter “ATOMOS ,” meaning “not to be cut.” To Democritus,

• Atoms were small, hard particles that were all made of the same material but were different shapes and sizes.

• Atoms were infinite in number, always moving and capable of joining together

1. Dalton’s Atomic theory:

• First recorded evidence that atoms existed.

• Using his theory, Dalton rationalized the various laws of chemical combination

Dalton's theory was based on the premise that the atoms of different elements could be distinguished by differences in their weights.

• Limitations

o The indivisibility of an atom was proved wrong , for, an atom can be further subdivided into protons, neutrons and electrons.
o The atoms of same element are similar in all respects , but isotopes of same element have different mass.
o Dalton's theory was based on the premise that the atoms of different elements could be distinguished by differences in their weights.

Discovered electrons in 1897.

• Showed us that the atom can be split into even smaller parts.

His discovery was the first step towards a detailed model of the atom .

• An atom is a uniform sphere of positive charges (due to presence of protons) as well as negative charges (due to presence of electrons).

• An electron is a negatively charged component of an atom which exists outside the nucleus. Each electron carries one unit of negative charge and has a very small mass as compared with that of a neutron or proton.

JJ Thomson used cathode ray tubes to demonstrate that the cathode ray responds to both magnetic and electric fields.

Since the ray was attracted to a positive electric plate placed over the cathode ray tube (beam deflected toward the positive plate) he determined that the ray must be composed of negatively charged particles. He called these negative particles "electrons."

Limitation: Model failed to explain how protons and electrons were arranged in atom so close to each other.
Eugene Goldstein:

"canal rays" which had electrical and magnetic properties opposite of an electron

Protons:

The canal rays have positively charged sub-atomic, particles known as protons (p).

Q.1 What was the model of an atom proposed by Thomson?
Q.2 What is the nature of charge on electrons?
Q.3 What are canal rays ?
Q.4 State the nature of the constituents of canal rays.

3. Rutherford’s Scattering Experiments:

Experiment: Rutherford took a thin gold foil and made alpha particles , [ He²⁺ ] positively charged Helium fall on it.

• Limitation: In Rutherford’s atomic model , Nucleus & electrons are held together by electrostatic force of attraction which would lead to the fusion between them. This does not happen in the atom.

Atomic radius ~ 100 pm = 1 x 10-¹⁰ m
Nuclear radius ~ 5 x 10-³ pm = 5 x 10-¹⁵ m

• In 1932, James Chadwick proved that the atomic nucleus contained a neutral particle which had been proposed more than a decade earlier by Ernest Rutherford officially discovered the neutron in 1932, Chadwick received the Nobel Prize in 1935.

A neutron is a subatomic particle contained in the atomic nucleus. It has no net electric charge, unlike the proton's positive electric charge.

Q.1 Who discovered the nucleus of the atom?Q.2 What is the charge on alpha particles ?
Q.3 Which observation of Rutherford’s scattering experiment established the presence large empty space in atom?
Q.4 What is the nature of charge on nucleus of atom?
Q.5 Who discovered neutron ?

4. Sub Atomic Particles:

Protons & Neutrons collectively are known as NUCLEONS.

Q.1 Why is the relative mass of an electron is taken as negligible ?
Q.2 Give the actual masses of electron & proton in kg?
Q.3 What are nucleons?

5.Atomic Number & Mass Number:

“Atomic number of an element is defined as the number of unit positive charges on the nucleus (nuclear charge) of the atom of that element or as the number of protons present in the nucleus.”

Atomic number, Z = Number of unit positive charge on the nucleus = Total number of unit positive charges carried by all protons present in thenucleus. = Number of protons in the nucleus (p) = Number of electrons revolving in the orbits (e)

Eg :- Hydrogen – Atomic number= 1 (1 proton)

Helium - Atomic number = 2 (2 protons)

Mass number[ A] : It is defined as the sum of the number of protons & neutrons present in the nucleus of an atom.

Mass Number = Mass of protons + Mass of neutrons

Eg :- Carbon – Mass number = 12 (6 protons + 6 neutrons) Mass = 12u Aluminium – Mass number = 27 (13 protons + 14 neutrons) Mass = 27

Q.1 The mass number of an element is 18. It contains 7 electrons .What is the number of protons and neutrons in it ?
Q.2 An atom contains 3 protons , 3 electrons and 4 neutrons . i) What is its atomic number ? ii) What is its mass number?
Q.3 An element is represented by . Give the number of electrons and neutrons in it.

6. Niel Bohr Atomic Model:

Main Postulates of the Bohr Model [refer NCERT Text Book article 4.3 ,page number-49]

Q.1 What happens when an electron jumps from lower to higher energy level?
Q.2 Which energy shell is nearest to the nucleus of an atom?
Q.3 Which energy shell has higher energy L or N ?

7. Electronic configuration & Valency:
Bohr and Bury Scheme - Important Rules

The outermost shell of an atom cannot accommodate more than 8 electrons, even if it has a capacity to accommodate more electrons. This is a very important rule and is also called the OCTET RULE. The presence45 of 8 electrons in the outermost shell makes the atom very stable.

Q.1 An atoms has atomic number 13. What would be its configuration.
Q.2 What is octet rule?
Q.3 How many electrons M shell can accommodate?
Q.4 If an atom has complete K and L shell, what would be its atomic number?

8. Isotopes & Isobars:
 

Q.1 Why atoms of isotopes are chemically same?
Q.2 Give the representation of three isotopes of carbon which are C-12 , C-13 and C-14.

QUESTION BANK [ *HOTS ]

1 Mark Questions:

1. Write the names of three elementary particles which constitute an atom.
2. Name the scientist & his experiment to prove that nucleus of an atom is positively charged.
3. Which is heavier , neutron or proton ?
4. *How many times a proton is heavier than an electron?
5. What was the model of an atom proposed by Thomson ?
6. How many electrons at the maximum can be present in the first shell ?
7. What type of charge is present on the nucleus of an atom?
8. Give the number of protons in <sup>35Cl₁₇
9. *What are iso bars ?
10. Name the particles which determine the mass of an atom.

2 Marks Questions:

1. Define the following terms: a) Atomic number b) Mass number
2. Write the charges on sub atomic particles. 47
3. Identify the isotopes out of A , B , C & D ? 33A₁₇ , 40B₂₀ , 37C ₁₇ , 38D₁₉
4.* Give one Achievement and one limitation of J.J Thomson’s model of atom?
5. What are valence electrons? Give example.
6. *Which kind of elements have tendency to lose electron ? Give example.
7. How many electrons are present in the valence shell of nitrogen & argon?
8. State the maximum capacity of various shells to accommodate electrons.
9. Give the symbol , relative charge & mass of the three sub atomic particles.
32 S₁₆ state :
i) Atomic number of sulphur, ii) Mass number of sulphur
iii) Electronic configuration of sulphur.

3. Marks Questions:

1. Why do Helium has Zero valency?
2. An atom contains 3 protons , 3 electrons and 4 neutrons .What is its atomic number , mass number & valency?
3. *How are the isotopes of hydrogen represented ?
4. Write the complete symbol for the atom with the given atomic number [Z] & mass number[A].</sup>

5 Marks Questions:

1.* a) Give the observations as well as inferences of Rutherford’s  Scattering experiment for  determining the structure of an atom.
      b) On the basis of above experiment write the main features of   atomic model.
2. Write the main postulates of Bohr’s Model of Atom.
 

• The scientists who discovered subatomic particles.
• Rutherford established the existence of nucleus.
• Difference between Atomic number and Mass number
• Electronic configuration & its relation with Valency.
• Difference between Isotope and Isobar.

MULTIPLE CHOICE QUESTIONS ON CHEMISTRY PRACTICALS

1. To prepare
   a) a true solution of common salt, sugar and alum   
   b) a suspension of soil, chalk powder and fine sand in water c) a colloidal of starch in water and egg albumin in water and distinguish between these on

1. Name the solute in common salt solution :

2 Pick out a colloid from the following :

3. Which of the following is property of true solution ?

4.The process of separation of insoluble solids from a liquid is called :

5. Which of the following mixtures is stable?

6. Egg albumin in water forms :

7. Which of the following represents a correct set of observations for a mixture of common salt and water

2. To prepare    a) a mixture    b) a compound
using iron filings and sulphur powder and distinguish between these on the basis of:
i. appearance i.e., homogeneity and heterogeneity
ii. behaviour towards a magnet
iii. behaviour towards carbon disulphide as a solvent.
iv. effect of heat.

1.The colour of sulphur is :

2. FeS is not attracted by magnet because :
 

4. In FeS , the particles of iron and sulphur are :

5. Iron reacts with sulphur to form FeS at :
 

6. When a mixture of iron fillings and sulphur is heated , the colour of the mixture changes from :
 

7. Which of the following has lowest melting point :
 

3. To carry out the following reactions and classify them as physical or chemical changes.

a. Iron with copper sulphate solution in water.
b. Burning of magnesium in air.
c. Zinc with dilute sulphuric acid
d. Heating of copper sulphate
e. Sodium sulphate with barium chloride in the form of their solutions in water.

1. The colour of hydrated copper sulphate is :
 

2. What happens when Zn granules react with dilute sulphuric acid :

3. Fe + CuSO₄ → FeSO₄ + Cu is an example of :

4. What happens when iron nails are added to copper sulphate solution :
 

5. BaSO₄ is :
 

6. Magnesium oxide , when placed on moist red litmus paper :
 

7. What is the nature of SO₂ :
 

4. To separate the components of a mixture of sand , common salt and ammonium chloride (or camphor) by sublimation. 1. Sublimation is the process in which :

a) Liquid changes into gaseous state
b) Solid changes into liquid state
c) Solid directly changes into gaseous form
d) Solid first converts into liquid , then into vapour form. 53

2. Which of the following substances sublimes on heating :

a) Iodine
b) Camphor
c) Naphthalene
d) All of these

3. In a mixture of sand, common salt and ammonium chloride , the substance that sublimes is:

a) Ammonium chloride
b) Sand
c) Common salt
d) All of these

4. Recovery of salt from salt solution in water can be done by :

a) Evaporation
b) Distillation
c) Filtration
d) None of these

5. What do you observe in the inner side of the funnel during sublimation of NH4Cl

a) Particles of white solid
b) Yellow fumes
c) Vapours of sodium chloride
d) No fumes are deposited

6. Which of the following mixtures cannot be separated by sublimation :

a) Ammonium chloride & sodium chloride
b) Ammonium chloride & sand
c) Ammonium chloride & iodine
d) Ammonium chloride & copper sulphate

7. A mixture of common salt and ammonium chloride is heated in a china dish covered with an inverted funnel with stem closed with a cotton plug. After the experiment the china dish will contain :

a) Common salt
b) Ammonium chloride
c) Both (a) and (b)
d) None of these.

5. To determine the melting point of ice and the boiling point of water.

1. Which of the following will help in determining the melting point of ice accurately ?

a) Ice made from tap water
b) Ice made from distilled water
c) Ice made mixed with salt
d) None of these 54

2. In determination of melting point of ice , the ice is contaminated with some non-volatile impurity, like common salt, melting point of ice will :

a) Increase
b) Decrease
c) May increase or decrease
d) Does not change

3. What is the melting point of ice?

a) 0^oC
b) 100^oC
c) 273 K
d) Both (a) and (c)

4. Which vessel is used to determine the melting point of ice ?

a) Beaker
b) R B Flask
c) Conical Flask
d) Measuring Flask

5. At what temperature ice and water both exist together under normal atmospheric pressure ?

a) Below 273.16 K
b) Above 273.16 K
c) At 273.16 K
d) None of these

6. In determining the boiling point of water , correct reading is obtained when :

a) Temperature start rising
b) Water starts boiling
c) Whole of water evaporates
d) Temperature becomes constant

7.Water evaporates faster :

a) In still air
b) In humid air
c) In dry air
d) In windy & dry air

6. To verify the law of conservation of mass in a chemical reaction.

1. What does the law of conservation of mass state?

a) It states that mass is neither created nor destroyed.
b) It states that mass can be created or destroyed.
c) It states that mass cannot be created but can be destroyed.
d) It states that mass can be created but cannot be destroyed. 55

2. If you melt 100 g of ice will you get the same mass of water ?
a) Yes
b) No
c) May be
d) Sometimes

3. State the chemical reaction between Barium Chloride (aqueous) & Sodium Sulphate (aqueous) .

a) BaC_l2 (aq) + Na₂SO₄ (aq) → BaSO₄ (white ppt) + 2NaCl (aq)
b) BaC_l2 (aq) + Na₂SO₄ (aq) → BaSO₃ (red ppt) + 2NaCl (aq)
c) Both (a) & (b)
d) None of these

4. Which of the following reaction does not conform to law of conservation of mass ?

a) Burning of candle
b) Melting of ice
c) Fusion reaction occurring in sun
d) Combustion of fuel

5. In the reaction 2NaN₂ .→ 2Na +3N₂ , if 850 g of NaN₂ is decomposed to give 265.20 g of Na , how much N2 is produced ?

a) 584.80 g
b) 265.20 g
c) 850 g
d) 484.20 g

6. In chemical reactions how does law of conservation of mass contribute in writing chemical equations ?

a) It does not help.
b) Equations can be balanced by writing their correct co – efficient
c) Both (a) and (b)
d) None of these

7. In accordance with the law of conservation of mass give the co-efficient of O₂ in the equation:

C5H₁₂+ O₂ → 5CO₂ + 6H₂O

a) 4
b) 6
c) 8
d) 2

Verification of “Law of Conservation of mass”

A solution of sodium chloride and silver nitrate are taken separately in the two limbs of an 'H' shaped tube.

The tube is sealed and weighed precisely. The two reactants are made to react by inverting the tube. The

following reaction takes place.

AgNO₃(aq) + NaCl (aq) • AgCl (s) + NaNO₃ (aq)

The whole tube is kept undisturbed for sometime so that the reaction is complete.

When the tube is weighed again it is observed that:

Weight before the reaction = Weight after the reaction

Limitation of “Law of definite proportion”

This law does not hold good when the compound is obtained by using different isotopes of the combining elements .

Q.1 Why chemical reactions are in accordance with the Law of conservation of mass?

Q.2 Calculate the ratio of atoms present in 5 g of magnesium and 5 g of iron.

[Atomic mass of Mg=24 u, Fe=56 u]

Law of Conservation of mass:

proposed by the French chemist Antoine Lavoisier (1774)

Mass can neither be created nor destroyed in a chemical reaction.

OR

For any chemical process in a closed system, the mass of the reactants must be equal the mass of the products.

C + O₂ = CO₂12g +32g = 44g

2. John Daltons Atomic Theory

Using his theory, Dalton rationalized the various laws of chemical combination which were in existence at that time. However, he assumed that the simplest compound of two elements

Q.1 In what respect does Dalton’s Atomic theory hold good even today?

Q.2 Which of the following is not the postulate of Dalton’s Atomic theory of matter ?

a) Each element is made up of extremely small particles called atoms.

b) Atoms of a given element are identical in chemical properties but have different

physical properties.

c) Atoms cannot be created nor destroyed.

d) Compounds are formed by the chemical union of atoms of two or more elements in fixed proportion .

3. Atoms ,Molecules, Ions Chemical Formula

• MOLECULES OF ELEMENT : The molecules of an element are constituted by the same type of atoms.

• MOLECULES OF COMPOUND: Atoms of different elements join together in definite proportions to form molecules of compounds.(hetero atomic molecules)

• ATOMICITY : The number of atoms contained in a molecule of a substance (element or compound) is called its atomicity.

• Based upon atomicity molecules can be classified as follows.

Monoatomic molecules: Noble gases helium, neon and argon exist as He Ne and Ar respectively.

Diatomic molecules: H₂ , O₂, N₂,C_l2, CO , HCl .

Triatomic molecules: O3 ,CO₂ , NO₂.

• SYMBOLS

• The abbreviation used to represent an element is generally the first letter in capital of the English name of element.

capital of the English name of element.

Oxygen • O Nitrogen • N

• When the names of two or more elements begin with the same initial letter, the initial letter followed by the letter appearing later in the name is used to symbolize the element Barium

• Ba Bismuth • Bi

Q.1 Give one example each of molecule of element & molecule of compound.

Q.2 How does an atom differ from molecule ?

Q.3 Name a triatomic gas.

Q.4 Name the element represented by Hg , Pb, Au.

Q.5 What is the difference between an atom of hydrogen and a molecule of hydrogen?

Polyatomic Ion : A group of atoms carrying a charge is as polyatomic ion.

eg: NH₄+ - Ammonium Ion ; CO₃²- Carbonate ion

Valency :The number of electrons which an atom can lose , gain or share to form a bond.

OR

It is the combining capacity of an atom of the element.

• Chemical Formula: A chemical formula is a short method of representing chemical elements and compounds.

Writing a Chemical Formula -CRISS-CROSS rule

EXAMPLES

Q.1 What is the difference between an anion & cation ?

Q.2 Write down chemical formula of

Q.3 Write chemical names of

4. Mole Concept

The mole (mol) is the amount of a substance that contains as many elementary entities as there are atoms in exactly 12.00 grams of ₁₂C

The Avogadro constant is named after the early nineteenth century Italian scientist Amedeo Avogadro.

GRAM MOLECULAR MASS

Gram molecular mass is the mass in grams of one mole of a molecular substance. Ex: The molecular mass of N₂ is 28, so the gram molecular mass of N₂ is 28 g.

ATOMIC MASS UNIT

An atomic mass unit or amu is one twelfth of the mass of an unbound atom of carbon-12. It is a unit of mass used to express atomic masses and molecular masses.

Also Known As: Unified Atomic Mass Unit

MOLECULAR MASS : A number equal to the sum of the atomic masses of the atoms in a molecule.

The molecular mass gives the mass of a molecule relative to that of the ₁₂C atom, which is taken to have a mass of 12. Examples: The molecular mass of C₂H₆ is approximately 30 or [(2 x 12) + (6 x 1)] . Therefore the molecule is about 2.5 times as heavy as the ₁₂C atom or about the same mass as the NO atom with a molecular mass of 30 or (14+16) .

Q.1 What term is used to represent the mass of 1 mole molecules of a substance?

Q.2 What is the gram atomic mass of i) Hydrogen ii) oxygen ?

Q.3 Calculate molar mass of C_2MH₂.

5.Molar Mass & Avogadro Constant

QUESTION BANK [ *HOTS ]

1 Mark Questions:

1. Who gave law of conservation of mass ?

2. What term is used to represent the mass of

1 mole molecules of a substance?

3. What name is given to the number 6.023 x 10 ²³ ?

4. What is molecular mass?

5. Give Latin names for sodium & mercury.

6.How many atoms are there in exactly 12 g of carbon ?

7. Define mole.

8. Calculate formula unit mass of CaCl₂. [ At. Mass : Ca = 40 u , Cl = 35.5 u ]

9. Name a diatomic gas.

10. How many atoms are present in H₂SO₄.

2 Marks Questions:

1. Give the chemical symbols for the following elements: Gold, Copper , Potassium & Iron.

2. What do the following symbols represent - i) 1 H & ii) H₂

3. Neon gas consists if single atoms , what mass of neon contain 6.022 x 10₂₃ atoms.

4. What elements do the following compounds contain ?

5. State the differences between an atom or a molecule.

6. Molar Mass of water is 18 g mol-₁ , what is the mass of 1 mole of water? .

7. *The number of atoms in 1 mole of hydrogen is twice the number of atoms in one mole of helium. Why?

8. Write the chemical formulas for the following:

9. Calculate molar mass of H₂O₂ & HNO₃.

10. What is the mass of 0.2 moles of oxygen molecules?

3 Marks Questions:

1. State the main postulates of John Dalton’s atomic theory.

2. What are polyatomic ions ? Give two examples.

3. State the following

4. What is the mass of :

5. What is meant by the term atomicity ? State the atomicity of

5. Marks Questions:

1.i) What is molecular formula ? State with example what information can be derived from a molecular formula .

ii) Write the names of the compounds represented by the following formulas:

2. i) What is gram molecular mass?

ii) Write the formulas & names of the compounds formed between :

3. i) Calculate the number of moles for the following:

ii) How many molecules are present in 34 g of ammonia ?

iii) Calculate the mass of 0.5 mole of sugar (C₁₂H₂₂O₁₁)

Elements

Elements are made up of one kind of atoms only. Compounds are made up of one kind of molecules only.

Difference between Compound &Mixture

Q.1 Is air around us a compound or mixture?
Q.2 Water is a compound. Justify.
Q.3 Classify the following as element , compound and mixture: Iron , sea water , Milk
Q.4 Are the naturally occurring material in nature chemically pure substances?

2. Types of Mixtures Mixtures can also be grouped

i) On the basis of their physical states:

SOLID

ii) On the basis of miscibility:

Q.1 Give one example for each of the following mixtures:

i) Solid/solid (homogeneous)

ii) Solid/solid (heterogeneous)

iii) Liquid/liquid (homogeneous)

iv)Liquid/liquid (heterogeneous)

v) Gas/liquid (homogeneous)..

Q.2 Classify the following as homogeneous & heterogeneous mixture:

i) sodium chloride &  water

ii) glucose & water

iii) sand & water

iv) air

4. Separating the components of a mixture

The components of a heterogeneous mixture can be separated by

1.Simple methods like :-

hand picking , sieving , & Winnowing

2.Special techniques like: -

i) Evaporation : a mixture of salt and water or sugar and water.

ii) Centrifugation : Butter from curd, Fine mud particles suspended in water.

iii) Decantation (Using separating funnel) : Oil from water.

iv) Sublimation : Camphor from salt,

v) Chromatography : Different pigments from an extract of flower petals.

vi) Distillation and fractional distillation : Separating components of Petroleum

vii) Magnetic separation: Iron pins from sand.

Q.1 Name the process you would use to :
         i) recover sugar from an aqueous sugar solution.
         ii) separate mixture of salt solution and sand.         

Q.2 How will you separate a mixture of sand , water and mustard oil ?        

5. Concentration of Solution

The amount of solute present in a given amount (mass or volume) of solution.
Concentration of a solution = Amount of solute / amount of solvent

The concentration of a solution can be expressed as mass by mass percentage or as mass by volume percentage.
Mass by mass percentage of a solution = Mass of solute × 100/ Mass of solution
Mass by volume percentage of a solution = Mass of solute ×100/Volume of solution

Types of Solutions

a) on the basis of size of solute particles:

[ Types of colloids ]

Colloidal solution is a heterogeneous mixture. It consists of two phases:-

(i) Dispersed phase : component present in small proportion

(ii) Dispersion medium : component present in large proportion

Tyndall effect

The particles of colloid are large enough to scatter a beam of light passing through it and make its path visible. Thus, they show Tyndall effect.

Brownian movement.

The colloidal particles are moving at random in a zigzag motion in all directions. This type

of zig-zag motion of colloidal particles is called Brownian movement.

b) On the basis of amount of solute:

c) On the basis of nature of solvent

Q.1 Classify the following substances into true solutions and colloidal solutions. Milk , ink , starch dissolved in water.
Q.2 A solution has been prepared by dissolving 5g of urea in 95 g of water. What is the mass percent of urea in the solution?
Q.3 Give an example of an aqueous solution in which gas is dissolved.

6.Physical & Chemical Changes

Physical changes

Changes that do not result in the production of a new substance.

• If you melt a block of ice, you still have H2O at the end of the change.
• If you break a bottle, you still have glass

Examples : melting, freezing, condensing, breaking, crushing, cutting, and bending.

Chemical changes

- Changes that result in the production of another substance.

• As in the case of autumn leaves, a change in color is a clue to indicate a chemical change.

• a half eaten apple that turns brown.

Q.1 Which of the following is an example of physical change?

a. Mixing baking soda and vinegar together, and this causes bubbles and foam.

b. A glass cup falls from the counter and shatters on the ground.

c. Lighting a piece of paper on fire and the paper burns up and leaves ashes.

d. Baking a birthday cake for your mother.

Q.2. Which of the following is an example of chemical change?

a. Filling up a balloon with hot air.

b. Taking a glass of water and freezing it by placing it in the freezer.

c. A plant collecting sunlight and turning it into food.

d. Your dog ripping up your homework.

Q3. Which change can be easily be reversed?

a. Chemical Change

b. Physical Change

c. Both a physical and chemical change

d. Neither a physical or chemical change

7.Alloys

A material that has metallic properties and is composed of two or more chemical elements of which at least one is a metal .

• These cannot be separated into their components by physical methods.

• However, these are considered as mixture because these show the properties of its

constituents and can have variable composition.

The benefit of alloys is that you can combine metals that have varying characteristics to create an end product that is stronger, more flexible, or otherwise desirable to manufacturers.

• Aluminium alloys are extensively used in the production of automotive engine parts.

• Copper alloys have excellent electrical and thermal performance, good corrosion

resistance, high ductility and relatively low cost.

• Stainless steel alloys are used for many commercial applications such as watch

straps, cutlery etc.

• Titanium alloys have high strength, toughness and stiffness & are used in aerospace

structures .

Q,1 Why should we use alloys instead of pure metals?

Q.2 State uses of Aluminium & Stainless steel alloys.

QUESTION BANK [ *HOTS ]

1 Mark Questions:

1. What is meant by pure substance?

2. What is meant by mass percentage of solution?

3. Name the process of separation of miscible liquids.

4. Arrange the following in decreasing order of size of the particles.
True Solution , Suspension , Colloid.

5. *Give an example of an aqueous solution in which gas is dissolved.

6. Name the dispersion medium and dispersed phase in the white material inside an egg.

7. What happens when hot saturated solution is cooled?

8. How would you separate a mixture of chalk and water?

9. *How much water should be added to 15 grams of salt to obtain 15 % salt solution?

10. What type of mixtures are separated by technique of crystallization ?

3.Marks Questions:

1. Classify the following into elements, compounds and mixtures:

2. Give any two applications of centrifugation.
3. Which of the following is chemical change?

4. *State the difference between simple distillation & fractional distillation.

5. * A solution contains 40 ml of ethanol mixed with 100 ml of water. Calculate the
concentration in terms of volume by volume percentage of the solution.

5 Marks Questions:

1. *What is meant by Tyndall effect? What is its cause? Illustrate with example.

2. How would you separate the mixture containing sulphur and sand ?

3. What is crystallization? Give its two applications.

4. How are sol, solution and suspension different from each other?

5. How do we obtain coloured components, i.e. dye from Blue/Black ink ?

You are expected to know………

• Types of mixtures.

• Method of Separation of mixtures.

• Types of solutions.

• Concentration terms of solution.

• Physical and Chemical Change.

• Significance of alloys.

Anything that occupies space and has mass and is felt by senses is called matter. Matter is the form of five basic elements the Panch tatva – air , earth ,fire , sky and water.

Characteristics of particles of matte

•Made of tiny particles.
•Vacant spaces exist in particles.
•Particles are in continuous motion.
•Particles are held together by forces of attraction.

States of Matter

Basis of Classification of Types

• Based upon particle arrangement
• Based upon energy of particles
• Based upon distance between particles

Five states of matter

SOLID	LIQUID	GAS
Fixed shape and definite volume .	Not fixed shape but fixed volume.	Neither fixed shape nor fixed volume.
Inter particle distances are smallest.	Inter particle distances are larger.	Inter particle distances are largest.
Incompressible.	Almost incompressible.	Highly compressible.
High density and do not diffuse.	Density is lower than solids and diffuse.	Density is least and diffuse.
Inter particle forces of attraction are strongest.	Inter particle forces of attraction are weaker than solids .	Inter particle forces ofattraction are weakest
Constituent particles are very closely packed.	Constituent particles are less closely packed.	Constituent particles are free to move about.

Plasma (non –evaluative)

• A plasma is an ionized gas.
• A plasma is a very good conductor of electricity and is affected by magnetic fields.
• Plasma, like gases have an indefinite shape and an indefinite volume. Ex. Ionized gas

Bose-Einstein condensate (non –evaluative)

• A BEC is a state of matter that can arise at very low temperatures.
• The scientists who worked with the Bose-Einstein condensate received a Nobel Prize for their work in 1995.
• The BEC is all about molecules that are really close to eachother (even closer than atoms in a solid).

Microscopic Explanation for Properties of Solids

1. Solids have a definite shape and a definite volume because the particles are locked into place.
2. Solids do not flow easily because the particles cannot move/slide past one another.
3. Solids are not easily compressiblebecause there is little free space between particles .

Microscopic Explanation for Properties of Liquids

1. Liquids are not easily compressible and have a definite volume because there is little free space between particles.
2. Liquids have an indefinite shape because the particles can lide past one another.
3. Liquids flow easily because the particles can move/slide past one another.

Microscopic Explanation for Properties of Gases

1. Gases are easily compressible because there is a great deal of free space between particles
2. Gases flow very easily because the particles randomly move past one another.
3. Gases have an indefinite shape and an indefinite volume becausethe particles can move past oneanother.

Microscopic Explanation for Properties of Plasmas

1. Plasmas have an indefinite shape and an indefinite volume because the particles can move past one another.
2. Plasmas are easily compressible because there is a great deal of free space between particles.
3. Plasmas are good conductors of electricity &are affected by magnetic fields because they are composed of ions

Microscopic Explanation for Properties of BEC

1. Particles are less energetic than solids because Exist at very low temperature .
2. Particles are literally indistinguishable because they are locked into same space
3. BEC shows superfluidity because Particles can flow without friction.

Interchange in states of matter

Matter Can Change its State
Water can exist in three states of matter –
• Solid, as ice ,
• Liquid, as the familiar water, and
• Gas, as water vapour.

Sublimation :

The changing of solid directly into vapours on heating & vapours into solid on cooling. Ex. Ammonium chloride , camphor & iodine.

a) Effect of change in temperature

The temperature effect on heating a solid varies depending on the nature of the solid & the conditions required in bringing the change .
• On increasing the temperature of solids, the kinetic energy of the particles increases which overcomes the forces of attraction between the particles thereby solid melts and is converted to a liquid.
• The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
• The melting point of ice is 273.16 K.
• The process of melting, that is, change of solid state into liquid state is also known as fusion.

b) Effect of Change of Pressure

• Increasing or decreasing the pressure can change the state of matter. Applying pressure and reducing temperature can liquefy gases.
• Solid carbon dioxide (CO₂ ) is stored under high pressure. Solid CO₂ gets converted directly to gaseous state on decrease of pressure to 1 atmosphere without coming into liquid state. This is the reason that solid carbon dioxide is also known as dry ice.

Latent Heat :

The hidden heat which breaks the force of attraction between the molecules during change of state.

Evaporation & Boiling

• Particles of matter are always moving and are never at rest. • At a given temperature in any gas, liquid or solid, there are particles with different amounts of kinetic energy.
• In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the forces of attraction of other particles and gets converted into vapour .
• This phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation.

Factors Affecting Evaporation

• The rate of evaporation increases with an increase of surface area.
• With the increase of temperature, more number of particles get enough kinetic energy to go into the vapour state.
• Humidity is the amount of water vapour present in air. The air around us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases.
• Wind speed : the higher the wind speed , the more evaporation.

Evaporation cause cooling.

The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation,

Evaporation Vs Boiling (differnce)

• Boiling is a bulk phenomenon. Particles from the bulk (whole) of the liquid change into vapour state.
• Evaporation is a surface phenomenon. Particles from the surface gain enough energy to overcome the forces of attraction present in the liquid and change into the vapour state.

Kelvin & Celsius Scale

• Kelvin is the SI unit of temperature, 0⁰ C =273.16 K. we take 0⁰C = 273 K.
• SI unit of temperature is Kelvin. T (K)= T ( ^o0C) +273
• Kelvin scale of temperature has always positive sign , hence regarded as better scale than Celsius.
• Atmosphere (atm) is a unit of measuring pressure exerted by a gas. The SI unit of pressure is Pascal (Pa):
• 1 atmosphere = 1.01 × (10 to the power 5) Pa. The pressure of air in atmosphere is called atmospheric pressure. The atmospheric pressure at sea level is 1 atmosphere, and is taken as the normal atmospheric pressure.

Important Questions For Class 9 Chapter 1 State of matter

Q.1 Define matter.
Q.2 What happens if you put copper sulphate crystals in water?
Q.3 A substance has a definite volume but no definite shape ? State whether this substance is a solid , a liquid or a gas.
Q.4 Arrange the following substances in increasing order of force of attraction between the particles. (a) Milk (b) Salt (c) Oxygen.
Q.5 A substance has neither a fixed shape nor a fixed volume . State whether it is a solid , a liquid or a gas.
Q.6 The melting point of a substance is below the room temperature . Predict its physical state.
Q.7 What is vapour ?
Q.8 Name the temperature at which the solid and liquid states of substance can exis together .
Q.9 What is the effect of pressure on boiling point?
Q.10 Name any two substances which sublime.
Q.11 Define Condensation.
Q.12 For any substance, why does the temperature remain constant during the change of state?
Q.13 Which is the slow process , Evaporation or Boiling ?
Q.14 State the effect of surface area on rate of evaporation.
Q.15 Why are we able to sip hot tea faster from saucer rather than from a cup?
Q.16 What is the SI unit of temperature?
Q.17 why kelvin scale of temperature is regarded as better scale than Celsius?

1 Mark Questions:

1. Pressure on the surface of a gas is increased. What will happen to the inter particle forces?
2. Name the three states of matter.
3. What happens when a liquid is heated ?
4. A gas can exert pressure on the walls of the container. Assign reason.
5. Convert the following temperature to Kelvin Scale (a) 100°C (b) 37°C
6. What is meant by density?
7. Give the characteristics of the particles of matter.
8. Water droplets seen on the outer surface of a glass containing ice-cold water is due to _____________ .
9. Change of gaseous state directly to solid state without going through liquid sate is called _____________________ .
10. __________________ is a surface phenomenon.

2 Marks Questions:

1. Define Latent heat of vaporisation.
2. Explain why temperature remain constant during the change of state of any substance?
3. Define Sublimation with examples.
4. *Do we sweat more on a dry day or humid day ? Justify your reason.
5. Why do we see water droplets on the outer surface of a glass containing ice cold water?
6. Convert the following temperature to the Kelvin scale (a) 25°C (b) 373°C
7. List two properties that liquids have in common with solids.
8. List two properties that liquids have in common with gases.
9. *What will happen to the melting point temperature of ice if some common salt is added to it? Justify your answer.
10. *How will you show that air has maximum compressibility?

3 Marks Questions:

1. Define the term (a) Latent heat of fusion (b) Latent heat of vaporization
2. *State the effect of (i) surface area (ii) nature of the liquid on the rate of evaporation.
3. *Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Why?
4. What is the physical state of water at 250°C, 100°C, 0°C?
5. Give reasons :
i) A sponge can be pressed easily; still it is called a solid.
ii) Water vapours have more energy than water at same temperature.
6 . What are intermolecular forces ? How are these related to the three states of matter ?
7. Is it possible to liquify atmospheric gases? If yes, suggest a method.

5 marks Questions:

1. a) What is meant by evaporation? What are the factors on which the rate of evaporation depend upon? b) How does evaporation causes cooling?
2. State the properties of all the five states of matter.
3. Define : Melting point , Freezing point & Boiling point

Chemicals which may be used for the treatment of diseases and for reducing the suffering from pain are called medicines or drugs.

The branch of science which makes use of chemicals for the treatment of disseases [therapeutic effect] is called chemotherapy.
Some important classes of drugs are

Antacid

The chemical substances which neutralize the excess acid in gastric juice and raise the pH to an appropriate level in stomach are raUed antacids.

The most commonly used antacids are weak bases such as sodium bicarbonate [sodium hydrogencarbonate, NaHCO₃), magnesium hydroxide [Mg(OH)₂] and aluminium hydroxide [Al(OH)₃].

Generally liquid antacids are more effective than tablets because .. have more surface area available for interaction and neutralisation acid.

Milk is a weak antacid.

Histamine stimulates the secretion of pepsin and hydrochloric acid. The drug cimetidine [Tegamet] was designed to prevent the interaction of histamine with the receptors present in the stomach Cimetidine binds to the receptors tbat triggers the release of acid the stomach. This results in release of lesser amount of acid. Now ranitidine (zantac), omeprazole and lansoprazole are used hyperacidity.

Tranquilizers (Psychotherapeutic Drugs)

Chemical substances used for the treatment of stress, anxiety, irritability and mild or even severe mental diseases, are known as tranquilizers. These affect the central nervous system and induce sleep for the patients as well as eliminate the symptoms of emotional distress. They are the common constituents of sleeping pills.

Noradrenaline is one of the neurotransmitter that plays a role in mood change. If the level of noradrenaline is low, the signal sending activity becomes low, and the person suffers from depression. In such situations antidepressant drugs are required. These drugs inhibit the enzymes which catalyse the degradation of noradrenaline. If the enzyme is inhibited, this important neurotransmitter is slowly metabolized and can activate its receptor for longer periods of time, thus counteracting the effect of depression. Iproniazid and phenelzine are two such drugs.

Barbituric acid and its derivatives viz. veronal, amytal, nembutal, luminal, seconal are known as barbiturates. Barbiturates are hypnotic, i.e., sleep producing agents.

Equanil is used to control depression and hypertension.

Non-hypnotic chlorodiazepoxide and meprobamate are relatively mild tranquilizers suitable for relieving tension.

Analgesics

Medicines used for getting relief from pain are called analgesics. These are of two types :

1. Narcotics

Drugs which produce sleep and unconsciousness are called narcotics. Mhese are habit forming drugs. For example, morphine and codeine. Morphine diacetate is commonly known as heroin.

2. Non-narcotics

These are non-habit forming chemicals which reduce mild to moderate llatn such as headache, toothache, muscle and joint pain, etc. These are also termed as non-addicti,ve. These drugs do not produce sleep unconsciousness. Aspirin (2-acetoxybenzoic acid) is most commonly used analgesic with antipyretic properties. Now these days because its anti-blood clotting action, aspirin is widely used to
heart-attacks.

Aspirin is toxic for liver and sometimes also causes bleeding from- stomach. So, naproxen, ibuprofen, paracetamol,dichlorofenac sodium are other widely used analgesics.

Antipyretics

These are the chemical substance which reduce body temperature during high fever. Paracetamol, aspirin, phenacetin (4-hydroxy acetanilide), analgin and novalgin, etc., are common antipyretics. Out of these, paracetamol (4-acetamidophenol) is most common.

Antimicrobials

An antimicrobial tends to kill or prevent development of microbes CII inhibit the pathogenic action of microbes such as bacteria, fungi and virus selectively.

[Sulpha drugs constitute a group of drugs which are derivatives of sulphanilamide and have great antimicrobial capacity, thus, these are widely used against diseases such as dyptheria, dysentry, tubercu losis, etc.]

In structure these drugs are analogues of p-amino benzoic acid Different types of antimicrobial drugs are as follows :

1. Antibiotics 

These are the substances (produced wholly or partially by chemical synthesis) which in low concentrations inhibit the growth of microorganisms or destroy them by intervening in their metabolic processes.

Antibiotics are products of microbial growth and thus, antibiotic therapy has been likened to ‘setting on.e thief against another’.

Antibiotics are of two types :

1. Bactericidal antibiotics have cidal (killing) effect on microbes. For example, penicillin, ofloxacin, amino glycosides, etc.
2. Bacteriostatic antibiotics have a static (inhibitory) effect on microbes. For example, erythromycin, tetracycline, chloramphenicol, etc

Penicillin was the first antibiotic discovered (by Alexander Fleming) in 1929. It is a narrow-spectrum antibiotic. Ampicillin and amoxicillin are semi-synthetic Illodifications of penicillin. Penicillin is not suitable to all persons and some Personsare allergic to it. Consequently, it is essential to test the patients for sensitivity (or allergy) to penicillin, before it is administered.

In India, penicillin is manufactured at Pimpri and Rishikesh (Uttarakhand).

Broad-spectrum antibiotics also called antibiotics, are antibiotics which are effective against different types of harmful microorganisms. e.g., Tetracycline,  chloramphenicoltgiven in case of typhoid, dysentery, fever ofloxacin, etc.

2. Antiseptics

These are the chemicals which either kill or prevent the growth microorganisms. Antiseptics are applied to the living tissues such wounds, cuts, ulcers and skin diseases in the form of antiseptic creams like furacin and soframycin. e.g., Some important examples of antiseptics are

(i) Dettol is a mixture of chloroxylenol and terpineol.

(ii) Bithional is added to soaps to impart antiseptic properties to reduce the odours produced by bacterial organic matter on the skin.

(iii) Tincture of iodine is a 2-3% solution of iodine in alcohol, which is a powerful antiseptic for wounds.

(iv) Iodoform (CHI₃) is also used as an antiseptic for wounds.

(v) Boric acid in dilute aqueous solution is weak anIUS4!pa eyes.

3. Disinfectants

These are the chemical substances which kill microorganisms not safe to be applied to the living tissues. They are generally kill the microorganisms present on inanimate objects such as drainage systems, instruments, etc.

Some common examples of disinfectants are as follows :

(i) 1% phenol solution is disinfectant while in lower concentration 0.2% solution of phenol is antiseptic.

(ii) 0.2-0.4 ppm aqueous solution of chlorine is used for sterilisation of water to make it fit for drinking purpose.

(iii) SO₂ at very low concentrations behaves like disinfectant.

(iv) Formaldehyde (HCHO) in the disinfecting rooms and operation gaseous theatres forms is used in hospitals. for

Antifertility Drugs

These are the chemical substances used to control the pregnancy. These are also called oral contraceptives. They belong to the class of natural products, known as steroids.

Birth control pills essentially contain a mixture of synthetic estrogen and progesterone derivatives. Norethindrone is widely used as antifertility drug.

Chemicals in Food

1. Artificial Sweetening Agents

Sucrose (table sugar) and fructose are the most widely used natural sweeteners. But they add to our calorie intake and promote tooth decay. To avoid these problems many people take artificial sweeteners.

Organic substances which have been synthesized in lab are known to be many times sweeter than cane sugar. Such compounds are known as artificial sweetening agents or artificial sweeteners.

Some important artificial sweeteners are given below :

(i) Saccharin (o-sulphobenzimide)

Discoveredby Johns- Hopkins in 1879 (University of USA).

It is the most popular artificial sweetener. It is 550 times as sweet as cane Sugar, since it is insoluble in water, so it is sold in the market as its soluble or calcium salt.

It is non-biodegradable so excreted from the body in urine (unchanged). Its use is of great value for diabetic persons and people who need to control intake of calories.

(ii) Aspartame

It is the methyl ester of the dipeptide derived from phenylalanine aspartic acid. It is also known as ‘Nutra sweet’.

It decomposes at baking or cooking temperatures and hence, can used only in cold food and soft drinks.

Aspartame has the same amount of calories as sugar (4 cal per gram).

Aspartame should not be used by people suffering from the genetic disease known as PKU (phenyl ketone urea). Because in such people decomposition of aspartame gives phenylpyruvic acid. Accumulation ~ phenylpyruvic acid is harmful especially to infants due to brain damage and mental retardation.

(iii) Alitame

It is quite similar to aspartame but more stable than aspartame. It is 2000 times as sweet as sucrose. The main problem for such sweetenerf
is the control of sweeteness of the substance to which it is added because it is high potency sweetener.

(iv) Sucralose

It is a trichloro derivative of sucrose. It’s appearance and taste are like sugar. It is stable at cooking temperature. It is almost 600 times 88 sweet as sucrose. However, it neither provides calories nor causes toot.1i decay.

(v) Cyclamate

It is N-cyclohexylsulphamate. It is only 20 times sweeter than cane sugar.

2. Food Preservatives

These are the chemical substances added to food to prevent their spoilage due to microbial growth (bacteria, yeasts and moulds) and to retain their nutritive value for longer periods .

The most commonly used preservatives include table salt, supgar, vegetable oil, vinegar, citric acid. spices and sodium benzonate (C₆H₅COONA). Salts of sorbic acid and propanoic acid are also used” preservatives for cheese, baked food, pickles, meat and fish products.

1. Sodium benzoate is metabolised by conversion into hioppuric acid (C₆H₅CONHCH₂COOH), which is ultimately urine. It is used in soft drinks and acidic foods.

2. Antioxidants like BHT(butylated hydroxytoluene) and BRA butylated hydroxyanisole) retard the action of oxygen on the food and help in the preservation of food materials.

Cleansing Agents

The word detergent means cleansing agent. Actually detergent word is derived from Latin word ‘detergere’ means “to wipe off”, Cleansing agents are the substance which remove dirt and have cleansing action in water. These are also called surfactants.

Detergents can be classified into two types.

1. Soapy detergents or soaps, and
2. Non-soapy detergents or soapless soap.

1. Soaps

Soaps are sodium or potassium salts of higher fatty acids (containing 15-18 carbon atoms) e.g., stearic acid, oleic acid and palmitic acid. Sodium salts of fatty acids are known as hard soaps while the potassium salts of fatty acids are known as soft soaps.

Hard soaps are prepared by cheaper oil and NaOH while soft soaps are Jlrepared by oil of good quality and KOH. The soft soaps do not contain freealkali, produce more lather and are used as toilet soaps, shaving SOapsand shampoos.

Preparation of soaps

Soaps containing ‘Sodium salts are formed by heating fat (glyceryl ester ~fatty acid) with aqueous sodium hydroxide solution. This reaction is known as saponification.

The solution left after removing the soap contains glycerol, which can be recovered by fractional distillation. To improve the quality of soaps desired colours, perfumes and medicinal chemical substances, added.

Types of Soaps

Different kind of soaps are made by using different raw materials.

1. Toilet soaps These are prepared by using better grade of fat or oil and care is taken to remove excess alkali. Colour and perfumes are added to make these more attractive.
2. Floating soaps These can be prepared by beating tiny bubbles into the product before it hardens.
3. Transparent soaps These are made by dissolving the in ethanol and then evaporating the excess solvent.
4. Medicated soaps Medicated soaps are prepared by some antiseptics like dettol or bithional.
5. Shaving soaps These contain glycerol to prevent drying. A gum called rosin is added while making them. It forms sodium rosinate which lather well.
6. Laundry soaps These sodium silicate, borax and contain sodium fillers like carbonate. sodium rosins
7. Soap Chips These are made by running a thin sheet of melted soap on a cool cylinder and scraping off the soaps in small broken pieces.
8. Soap grannules These are dried miniature soap bubbles.
9. Soap powder and scouring soaps These contain a scouring agent (abrasive) such as powdered pumice or finely divided sand and builders like sodium carbonate and trisodium phosphate. Builders make the soaps act more quickly.

Disadvantages of Soaps

Soap is good cleansing agent and is 100% biodegradable microorganisms present in sewage water can completely oxidise soap to CO₂, As a result, it does not create any pollution problem. However soaps have two disadvantages:

(i) Soaps cannot be used in hard water since calcium magnesium ions present in hard water produce curdy precipitates of calcium and magnesium soaps.

These insoluble soaps separate as scum in water and causes hinderance to washing because the precipitate adheres onto the fibre of the cloth as gummy mass. Thus, a lot of soap is wasted if water. is hard.

(ii) Soaps cannot be used in acidic solutions since acids precipitate the insoluble free fatty acids which adhere to the fabrics and thus, reduce the ability of soaps to remove oil and grease from fabrics.

Soapless Soap/Synthetic Detergents

Synthetic detergents have all the properties of soaps but actually does not contain any soap, so they are known as ‘soapless soaps’.

Straight chain alkyl group containing detergents are biodegradable whereas branched chain alkyl group containing detergents are non-biodegradable.

Unlike soaps, synthetic detergents can be used in both soft and hard water. This is due to the reason that calcium and magnesium salts of detergents like their sodium salts are also soluble in water. Synthetic

detergents are mainly classified into three categories:

1. Anionic Detergents

These are sodium salts of sulphonated long chain alcohols or hydrocarbons.

(i) Alkyl hydrogen sulphates formed by treating long chain alcohols with concentrated sulphuric acids are neutralised with alkali to form anionic detergents.

(ii) Alkyl benzene sulphonates are obtained by neutralising alkyl benzene sulphonic acids with alkali.

In such detergents, the anionic part of the molecule is involved in the cleansing action.

They are mostly used for household work and in tooth paste

2. Cationic Detergents

These are quaternary ammonium salts of arnines with acetates, chlorides or bromides as anion. For example,

Cationic detergents are used in hair conditioner. They have germicidal properties but are expensive therefore, these are of limited use.

3. Non-ionic Detergents

Such detergents does not contain any ion in their constitution. One  such detergent can be obtained by reaction of stearic acid and polyethylene glycol.

Liquid dish washing detergents are non-ionic type, Mechanism of cleansing action of this type of detergents is the same as that of soaps.

Advantages of syntbeti.c detergents over soaps

1. Synthetic detergents can be used even in case of hard water whereas soaps fail to do so.
2. Synthetic detergents can be used in the acidic medium while soaps cannot because of their hydrolysis to free acids.
3. Synthetic detergents are more soluble in water and hence, form better lather than soaps.
4. Synthetic detergents have a stronger cleansing action than soaps.

Chemistry in Colouring Matter

The natural or synthetic colouring matter which are used in solution to stain materials especially fabrics are called dyes.

All colouring substances are not dyes, e.g., azobenzene, a coloured substance does ‘not act as dye.

A dye have following characteristics :.

1. It must have a suitable colour.
2. It can be fixed on the fabric either directly or with the help of mordant.
3. It must be resistant to the action of water, acid and alkalies. The groups, responsible for colour, are called chromophore, e.g.,

Classification of Dyes on the Basis of Constitution

(i) Nitro or nitroso dye Chromophore NO₂ or NO group, Auxochrome = -OH group, e.g., picric acid, martius yellow, Gambine, naphthol yellow-S.
(ii) Azo dye, e.g., bismark brown, methyl orange, methyl red, congo red, etc.
(iii) Anthraquinone dye e.g., alizarin
(iv) Indigo is the oldest known dye. Other examples are tyrian purple, indigosol.
(v) Phthalein dye e.g., phenolphthalein, fluorescein, eosin, mercurochrome.
(vi) Triarybnethane dye, e.g., malachite green, rosaniline.

Classification of Dyes on the Basis of Application

(i) Direct dyes These dyes applied directly to fibre and are more useful to the fabrics containing H-bonding like cotton, rayon, wool, silk and nylon, e.g., martius yellow, congo reu/etc.

(ii) Acid dyes These are water soluble and contain porar/acidic groups which interact with the basic group of e.g., Orange-I, congo red, methyl orange, etc. These dyes does not have affinity for cotton but are used for silk, wool, etc.

(iii) Basic dyes These dyes contain basic group (like NHz group) and react with anionic sites present on the fabric. These are used to dye nylons and polyester, e.g., butter yellow, magenta (rosaniline), aniline yellow, etc.

(iv) Vat dyes Being water insoluble, these cannot be applied directly. These are first reduced to a colourless soluble form by a reducing agent in large vats and then, applied to fabrics. After applying, these are oxidised to insoluble coloured form by exposure. to air or some oxidising agents, e.g., Indigo, tyrian purple, etc.

(v) Mordant dyes These are applied with the help of a binding material (e.g., metal ion, tannic acid or metal hydroxide) called mordant. Depending upon the metal ion used, the same dye can give different colours. Alizarin is an important example of such dyes.

(vi) Ingrain dye These dyes are synthesised directly on the fabric. These are water insoluble and particularly suitable for cotton fibres. Azo dyes belong to this group of dye.

Chemistry in Cosmetics

Cosmetics are used for decorating, beautifying or improving complexion of skin. Some of the cosmetics of daily use are as

1. Creams

These are stable emulsions of oils or fats in water and contain emmollients (to prevent water loss) and humectants (to attract water) as two fundamental components.

2. Perfumes

These solutions have pleasent odour and invariably consist of three ingredients: a vehicle (ethanol + H20), fixative e.g., sandalwood oil, benzoin, glyceryl diacetate etc.) and odour producing substance (e.g., terpenoids like linalool, anisaldehyde (p-methoxy- benzaldehyde etc.)

3. Talcum Powder

It is used to reduce irritation of skin. Talc (Mg₃(OH)₂Si₄O₁₀), chalk, Zno, zinc sterate and a suitable perfume are the constituents of talcum powder.

4. Deodorants

These are applied to mask the body odour. These possess antibacterial properties. Aluminium salts, ZnO, Zn0₂, (C₁₇H₃₅COO)₂Zn can be used in deodorant preparation.

Rocket Propellants

Substances used for launching rockets are called rocket propellants. These are the combination of an oxidiser and a fuel.

Depending upon the physical states of oxidiser and fuels, rocket propellants are classified as

1. Solid Propellants

These are further divided into two classes

(i) Composite propellants In these propellants, fuel is polymeric binder such as polyurethane or polybutadiene and oxidiser is ammonium per chlorate or potassium perchlorate.

The sequence that relates biomolecules to living organism is

Biomolecules → Organelles → Cells → Tissues → Organs → Living organism.

Carbohydrates

Optically active polyhydroxy aldehydes (aldcses) or ketones (ketoses) or compounds which on hydrolysis give these units are known as carbohydrates. They are also called saccharides

(Latin Saccharum = sugar) due to sweet taste of simpler members.

Depending upon their behaviour towards hydrolysis, carbohydrates can be of following three types

Monosaccharides

These cannot be hydrolysed to simpler molecules and further subdivided into tetroses, pentoses or hexoses depending upon the number of carbon atoms. These are also called homopolysaccharides.

• Aldotetroses Erythrose, Threose
• Aldopentoses Xylose, Ribose,
• Aldohexoses Glucose, Galactose,
• Ketohexoses Fructose

All naturally occurring monosaccharides belong to D-series.

killiani synthesis is used to convert an aldose into next higher aldose.

Oligosaccharides

(Greek oligos = few). On hydrolysis, they generally give two to nine monosaccharides (same or different) and are further classified as disaccharides, e.g., sucrose, maltose, lactose, trisaccharides and so on. C₁₂H₂₂O₁₁ is a disaccharide because it gives two monosaccharides.

The bond formed between two monosaccharides is called a glycosidic bond and normally it is (1, 4) bond.

Sucrose is most abundant in plants and known as cane sugar or table sugar or invert sugar as equimolar mixture of glucose and fructose is obtained by hydrolysis of sucrose.

Trisaccharides Raffinose (C₁₈H₃₂O₁₆)

Polysaccharides

These are polymers of monosaccharides. Examples are starch, cellulose, glycogen, etc.

1. Starch, (C₆H₁₀O₅)_N

It is a polymer of a-glucose and a major reserve food in plants. It turns blue with iodine. It is a mixture of two components:

1. Amylose (20%), an unbranched water soluble polymer.
2. Amylopectin (80%), a branched water insoluble polymer.

Sources of starch are potatoes, wheat, rice, maize, etc.

2. Cellulose, (C₆H₁₀O₅)_n

It is the most abundant and structural, polysaccharide of plants. It is important food source of some animals It is a polymer of D (+) β-glucose.

The chief sources of cellulose are wood (Contains 50% cellulose rest being lignin, resins, etc) and cotton (contains 90% cellulose rest being fats and waxes).

Several materials are obtained from cellulose:

1. Mercerised cotton Cellulose treated with cone. sodium hydroxide solution acquire silky lustre. It is called mercerissd cotton.
2. Gun cotton It is completely nitrated cellulose (cellulose nitrate), highly explosive in nature and is used in the manufacture of smokeless gun powder, called blasting gelatin.
3. Cellulose acetate It is used for making acetate rayon and motion picture films.
4. Cellulosexanthate It is obtained by treating cellulose with sodium hydroxide and carbon disulphide and is the basic material for VISCOSE rayon.

Oligosaccharides and heteropolysaccharides are also called heteropolysaccharides.

Reducing and Non-reducing sugars

Based upon reducing and non-reducing properties, carbohydrates are classified as reducing and non-reducing sugars. Carbohydrates reducing Fehling reagent or Tollen’s reagent are termed as reducing carbohydrates. e.g., All monosaccharides and disaccharides (except sucrose). But carbohydrates which do not reduce such reagents are known as non-reducing carbohydrates. e.g., sucrose and polysaccharides.

Sugars and Non-sugars

On the basis of their, taste, carbohydrates are classified as sugars and non-sugars. The monosaccharides and oligosaccharides having sweet taste are collectively known as sugars. Polysaccharides which are insoluble in water and not sweet in taste, are non-sugars.

Glucose

Dextrose, grape sugar, corn sugar, blood sugar (C₆H₁₂O₆).

Manufacture

By hydrolysis of starch with hot dil mineral acids and by hydrolysis of sucrose.

Extra glucose is stored in liver as glycogen.

α and β glucose

In intermolecular hemiacetal formation (cyclic structure), -CHO is converted into -CHOH which can have two configurations as shown below.

Glucose having (i) configuration about C₁ is the α-glucose and having (ii) configuration about C₁ is β-glucose.

The carbon C₁ is known as anomeric carbon and these compounds are called anomers. Both the forms are optically active. ex-D-glucosehas specific rotation +111.5° and β-D-glucose has specific rotation + 19.5°.

Mutarotation

When either of the two forms of glucose is dissolved in water, there is a spontaneous change in specific rotation till the equilibrium value of +52.5°. This is known as mutarotation.

Properties of glucose

Glucose has one aldehyde group, one primary hydroxyl (-CH₂OH) and four secondary hydroxyl (-CHOH) groups and gives the following reactions:

These reactions confirm the presence ofa carbonyl group in glucose.

(iii) Glucose reduces ammoniacal silver nitrate solution (Tollen’s reagent) to metallic silver and also Fehling’S solution or Benedict solution to reddish brown cuprous oxide (Cu₂O) and itself gets oxidised to gluconic acid. This confirms the presence of an aldehydic group in glucose.

(iv) With mild oxidising agent like bromine water, glucose is oxidised to gluconic acid. Glucose on oxidation with nitric acid gives saccharic acid.

(vii) Glucose on reaction with methyl alcohol in the presence of dry HCl(g) forms α and β-methyl glycosides. The reaction occurs only at the OH of hemiacetylic carbon.

Cyclic structure of glucose Given by Haworth and Hirst.

Fructose Fruit Sugar (C₆H₁₂O₆)

Manufacture

By hydrolysis of inulin.

α and β-fructose

The two forms have different configuration about C₂.

Fructose does not reduce Br₂ water.

Epimers

Monosaccharides differing in configuration at a carbon other than anomeric carbon are called epimers, e.g., glucose and galactose differ in configuration at C₄, hence called epimers.

Osazones

Monosaccharides and reducing disaccharides react with excess of phenyl hydrazine to form crystalline substances of the structure

It is known as osazones glucose and fructose give same osazone.

Molisch Test for Carbohydrates

In aqueous solution of compound add solution of α-naphthol in alcohol and then cone. H₂SO₄ along the walls of the test tube. Purple coloured ring is obtained at the junction.

Amino Acids
The compounds containing amino group (-NH₂) and carboxylic group (-COOH) are called amino acids.

R = H, alkyl or aryl group. Except glycine (H₂N.CH₂COOH), others are optically active in nature.

Classification of Amino Acids

Essential and Non-essential Amino Acids

Human body can synthesise ten amino acids, called non-essential amino acids. The remaining ten amino acids required for protein synthesis are not synthesised by body and are called essential amino acids. They are

1. Phenylalanine
2. Histidine
3. Tryptophan
4. Valine
5. Methionine
6. Threonine
7. Arginine
8. Leucine
9. Isoleucine
10. Lysine

Nomenclature

They are known by their common names and abbreviated by first three letters of their common names e.g., glycine as ‘gly’ and alanine a as ‘ala’.

Peptides

Peptides are condensation products of two or more amino acids.

Two molecules of different amino acids can form two dipeptides.Three molecules of different amino acids can give six tripeptides.

Dipeptide has only one peptide bond, tripeptide has two peptide bonds and so on. Thus, a polypeptide made up of n-amino acids has (n – 1) peptide bonds.

Polypeptides

Condensation Products of many amino acids ( ‘In P xiucts of many amino acids (≈ 10000) is known as polypeptide and those polypeptides which have molecular mass above than 10000 are called proteins.

Proteins

They are linear polymers of a-amino acids.

Structure of Proteins

(a) Primary structure

It simply reveals the sequence of amino acids.

(b) Secondary structure α-helix structure maintained by hydrogen bonds or β-pleated sheet structure when R is small group.

(c) Tertiary structure The folding and superimposition of polypeptide chains forms a compact globular shape, termed as tertiary structure. It is stabilised by covalent, ionic, hydrogen and disulphide bonds.

The precise arrangement constitutes the quaternary structure.

Classification on the Basis of Hydrolysis Products

(i) Simple These yield only a-amino acids upon hydrolysis.

e.g., albumin.

(ii) Conjugated proteins These yield α-amino acids and non-protein part, called prosthetic group.

(iii) Derived proteins These are obtained by partial hydrolysis of simple or conjugated proteins.

Proteins → Proteoses → Peptones → Polypeptides

Classification on the Basis Functions

1. Structural proteins Fibrous proteins
2. Enzymes Serve as biological catalyst e.g., pepsin, trypsin etc.
3. Hormones Insulin
4. Contractile proteins Found in muscles, e.g., myosin, actin.
5. Antibodies Gamma globulins present in blood.
6. Blood protein Albumms, haemoglobin and fibrinogen.

Haemoglobin is a globular protein. Its prosthetic group is heme. It Contains 574 amino acid units distributed in four polypeptide chains.

Two chains containing 141 amino acid residues each are called α-chains and the two chains containing 146 amino acid residues are called β-chains.

Sickle cell anaemia is caused by defective haemoglobin obtained by replacing only one amino acid, i.e., glutamic acid by valine.

Denaturation of Proteins

The process that changes the three dimensional structure of native proteins is called denaturation of proteins. It can be caused by Change in pH, addition of electrolyte, heating or addition of solvent like water, alcohol or acetone.

Tests of Proteins

(i) Biuret Test

Protein solution + NaOH + dil. CuSO₄ → pink or violet colour.

(ii) Millon’s Test

Protein solution + Millon’s reagent → pink colour

Millon’s reagent is solution of mercuric nitrate and nitrite in nitric acid containing traces of nitrous acid.

(iii) Iodine reaction

Protein solution + iodine in potassium iodide solution → yellow colour.

(iv)Xanthoprotic test

Enzymes

Enzymes constitute a group of complex proteinoid compounds, produced by living organisms which catalyse the chlemical reaction.

Non-proteinous components enhance the activity of certain enzymes and are known as co-enzymes. These include metal ions like Mn²⁺, Mg²⁺, K⁺, Na⁺, Zn²⁺, Co²⁺ etc., heterocyclic ring systems (pyrrole, purine, pyridine, etc.), a sugar residue, phosphoric acid residue of vitamins like thiamine, riboflavin etc.

Endoenzyme acts in the same cell in which it is synthesised, while exo-enzyme acts outside the cell in which it is synthesised.

Nomenclature

They are usually named by adding the suffix ‘ase’ to the root name of the substrate e.g., urease, maltase, diastase, invertase, etc.

Oxidative Enzymes

They catalyse oxidation-reduction reaction and are mostly conjugated proteins.

Some Common Enzyme

Characteristic Features of Enzymes

1. Rate of reaction They increase the rate of reaction up to 10⁶ to 10⁷ times.
2. Specific nature Urease catalyse the hydrolysis of urea and not methyl urea, so these are specific in nature.
3. Optimum temperature It is about 20-30°C.
4. pH of medium It is about 7 but for pepsin, it is 1.8·2.2 and for trypsin, it is 7.5-8.3.
5. Concentration Dilute solutions are more effective.
6. Amount of enzyme Very small amount can accelerate the reaction.
7. Enzyme inhibitors These compounds inhibit the enzyme action. With the help of such compounds, the reaction can be controlled.

Mechanism of Enzyme Action

Enzyme + Substrate → [Enzyme substrate] → Product + Enzyme Activated complex

Applications of Enzymes

(i) Treatment of diseases The congenital disease phenyl ketonurie caused by phenylalanine hyroxylase can be cured by diet of low phenylalanine content. Enzyme streptokinase is used for blood clotting to prevent heart disease.

(ii) In industry Tanning of leather, fermentation process etc.

Nucleic Acids

Important Terms of Nucleic Acids

1. Nucleotldes

Nucleotides consist of 5-carbon sugar + nitrogenous base + 1, 3-phosphate groups.

2. Pentose sugar

It is either ribose or deoxy ribose (not having oxygen at C₂).

3. Nitrogenous base

Derived from purines having two rings in their structure e.g., Adenine (A) and Guanine (G) and derived from pyrimidines having one ring in their structure e.g.,

Thymine (T), Uracil (U) and Cytosine (C).

Two H-bonds are present between A and T (A = T) while three H-bonds are present between C and G (C ≡ G).

4. Ribonucleotide

Phosphate unit + Ribose + one base unit from A, G, C, or U.

5. Deoxyrlbo nucleotide

Phosphate unit + Deoxyribose + one base from A, G, C or T.

6. Nucleoside

Ribose-/deoxyribose + one base unit from A, G, C, Tor U.

DNA and RNA

Nucleic acid is polynucleotide, present in the living cells or bacterial cells having no nucleus and in viruses having no cells.

(i) DNA Deoxy ribonucleic acid.

DNA + H_{2O → Phosphoric acid + deoxyribose + A, G, C, T}

(ii) RNA Ribonucleic acid

RNA + H_{2O → Phosphoric acid + Ribose + A, G, C, U}

Structure of DNA

It consists of two polynucleotide chains, each chain form a right handed helical spiral with ten bases in one turn of the spiral. The two chains coil to double helix and run in opposite direction. These are held together by hydrogen bonding.

Structure of RNA

It is usually a single strand of ribonucleotides and take up right handed helical conformation. Up to 12000 nucleotides constitute an RNA.

It can base pair with complementary strands of DNA or RNA according to standard base pairing rules-G pairs with C, A pairs with U or T. The paired strands in RNA-RNA or RNA-DNA are anti parallel as in DNA.

In both DNA and RNA, heterocyclic base and phosphate ester linkages are at C₁ and C₅‘ respectively of the sugar molecule.

Types of RNA

1. Messanger RNA (m-RNA) It is produced in the nucleus and carries information for the synthesis of proteins.
2. Transfer RNA (Soluble or Adoptive RNA) (s-RNA, t-RNA) It is found in cytoplasm. Its function-is to collect amino acids from cytoplasm for protein synthesis.

Functions of Nucleic Acids

1. Direct the synthesis of proteins.
2. Transfer the genetic information (hereditary characters).

Replication

It is a process in which a molecule of DNA can duplicate.

Template It means pattern. In the process of replication of DNA, the parent strand serves as template.

Gene The portion of DNA carrying information about a specific protein is Called gene.

Genetic code The relation between the amino acid and the nucleotide triplet is called genetic code.

Codons The nucleotide bases in RNA function in groups of three (triplet) in coding amino acids. These base triplets are called codons.

The world code is used with reference to DNA, codon with reference to m-RNA and anticodon with reference to t-RNA.

Lipids

The constituents of animals and plants soluble in organic solvents (ether, chloroform. carbon tetrachloride), but insoluble in water are called lipids. (Greek lipose = fat)

Types of Lipids

(i) Simple lipids

(a) Fats and oils on hydrolysis give long chain fatty acids + glycerol.

(b) Waxes Long chain fatty acids + long chain alcohols.

Vegetable and animal oils and fats have similar chemical structure and are triesters of glycerol, called glycerol.

Simple glycerides contain one type of fatty acids. Mixed glycerides contain two or three types of fatty acids.

Common saturated fatty acids CH₃-(CH₂)_nCOOH.

When n = 4 caproic acid; n = 6 caprylic acid; n = 8 capric acid, n = 10 lauric acid n = 12 myristic acid; n = 14 palmitic acid, n = 16 stearic acid.

Common unsaturated acids

C₁₇H₃₃COOH oleic acid; C₁₇H₃₃COOH linoleic acid.

Difference between oils and fats Oils are liquids at ordinary temprature (below 20° and contain lower fatty acids or unsaturated fatty acids.

Fats are solids or semisolids above 20°C and contain higher saturated fatty acids. Oils and fats act as “energy reservoirs” for the cells.

(ii) Phospholipids Phosphate + glycerol + fatty acids + a nitrogen containing base.

Function of phospholipids are

1. As emulsifying agents since they carry hydrophilic polar groups and hydrophobic non-polar groups.

2. They absorb fatty acids from the intestine and transport to blood cells.

(iii) Glycolipids They contain one or more simple sugars and are important components of cell membranes and chlorplast membranes.

(iv) Steroids and Terpenes Menthol, camphor are common plant terpenes. Carotenoids and pigments are also terpenes.

(a) Essential oils The volatile, sweet smelling liquids obtained from flowers, leaves, stems, etc. Example of terpenes are esters of lower fatty acid, e.g., clove oil, rose oil, lemon oil.

(b) Drying oils The oils which are converted into tough, transparent mass when exposed to air by oxidation polymerisation process are called drying oils. e.g., Linseed oil, perilla, poppy seed oils.

Cotton seed oil and til oil are semidrying oils.

Acid Value

It is the number of milligrams of KOH required to neutralise the free acid present in 1 g of oil or fat.

Saponification Value

It is the number of milligrams of KOH required to saponify 1g of oil or fat or the number of milligrams of KOH required to neutralise the free acidresulting from the hydrolysis of 1 g of an oil or fat.

Iodine Value

It is the number of grams of iodine absorbed by 100 g of oil or fat.

Relchert-Meissel Value (R/M Value)

It is the number of cc of N/10 KOH required to neutralise the distillate of 5 g of hydrolysed fat.

Blood

An average person has about 6.8 L of blood which is about 6-10% of the body weight. pH of blood is about 7.4.

Haemoglobin is globular protein. It is made up of four polypeptide chains which are arranged in tetrahedral manner. Each chain is associated with a non-protein part, called haem.

Haemoglobin

These axe the chemical substances which are produced by ductless glands in the body. Hormones acts as chemical messengers.

Some examples of ductless ‘(endocrine) glands are thyroid, pitutary, adrenal, pancreas, testes and ovaries.

Hormones are divided into three types:

1. steroids
2. proteins or polypeptides
3. amines.

Insulin is a protein hormone which is secreted by β-cells of the pancreas. Insulin was the first polypeptide in which the amino acid sequence was experimentally determined. Its deficiency leads to diabetes mellitus.

Vitamins

The organic compounds other than carbohydrates, proteins and facts which are required by body to maintain normal health, growth and nutrition are called vitamins.

The vitamins are complex organic molecules. They are represented by letters such as A, B, C, D, E, K.

Vitamins are broadly classified into two types,

1. Water soluble vitamins and
2. oil soluble vitamins.

Vitamins A, D, E and K are oil soluble whereas vitamins B and C are water soluble. Vitamin H is neither fat soluble nor water soluble.

Polymerisation

The process by which the monomers get combined and transformed into polymers. is known as polymerisation.

n [Monomer] → Polymer

Difference between Polymers and Macromolecules

Polymers are also called macromolecules due to their large size but converse is not always true. A macromolecule mayor may not contain monomer units, e.g., chlorophyll (C₅₅H₇₂O₅N₄Mg) is a macromolecule but not a polymer since there are no monomer units present so we can conclude that all polymers are macromolecules while all macromolecules may not be polymers in nature.

Classification of Polymers Based on Source of Origin

(i) Natural polymers Those polymers which occur in nature. i.e., in plants or animals. are called natural polymers.

(ii) Synthetic polymers The polymers which are prepared in the laboratory are known as synthetic polymers or man-made polymers, e.g., polythene, synthetic rubber, PVC, nylon-66, teflon, orlon etc.

(iii) Semisynthetic polymers Polymers obtained by making some modification in natural polymers by artificial means, are known as semi synthetic polymers, e.g., cellulose acetate (rayon), vulcanised rubber etc.

Classification of Polymers Based on Structure

(i) Linear polymers These are the polymers in which the monomer units are linked to one another to form long linear chains. These linear chains are closely packed in space. The close packing results in high densities, tensile strength and high melting and boiling points. e.g., high density polyethene, nylon and polyesters are linear polymers.

(ii) Branched chain polymers In such polymers, the monomer units are linked to form long chains with some branched chains of different lengths with source. As a result of branching, these polymers are not closely packed in space. Thus, they have low densities, low tensile strength as well as low melting and boiling points. Some common examples of such polymers are low density polyethene, starch, glycogen etc.

(iii) Cross-linked polymers or network polymers In such polymers, the monomer units are linked together to form three dimensional network. These are expected to be quite hard, rigid and brittle. Examples of cross linked polymers are bakelite, glyptal, melamine-formaldehyde polymer etc.

Classification of Polymers Based on Mode of Polymerisation

(i) Addition polymers The polymers formed by the polymerisation of monomers containing double or triple bonds (unsaturated compounds) are called addition polymers. Addition polymers have the same empirical formula as their monomers.

Addition polymers can further be classified on the basis of the types
of monomers into the following two classes:

Homopolymers The polymers which are obtained by the polymerisation of a single type of monomer are called homopolymers.

Copolymers The polymers which are obtained by the polymerisation of two or more monomers are called copolymers

(ii) Condensation polymers The polymers which are formed by the combination of monomers with the elimination of small molecules such as water, alcohol, hydrogen chloride etc., are known as condensation polymers, e.g., nylon 6,6 is formed by the condensation of hexamethylene diamine with adipic acid.

Classification of Polymers Based on Molecular Forces

1. Elastomers These are rubber like solid polymers in which the polymer chains are held together by weakest intermolecular forces, e.g., natural rubber, buna-S, buna-N etc . The weak binding forces permit the polymers to be stretched. A few ‘cross links’ are introduced in between the chains, which help the polymer to retract to its original position after the force is released as in vulcanised rubber.
2. Fibres Fibres belong to a class of polymers which are thread-like and can be woven into fabrics. These are widely used for making clothes, nets, ropes, gauzes, etc. Fibres possess high tensile strength because the chains possess strong intermolecular forces such as hydrogen bonding. The fibres are crystalline in nature and have sharp melting points. A few examples of this class are nylon-66, terylene and polyacrylonitrile.
3. Thermoplastics These are linear polymers and have weak van der Waals’ forces acting in the various chains. These forces are intermediate of the forces present in the elastomers and in the fibres. When heated, they melt and form a fluid which sets into a hard mass on cooling. Thus, they can be cast into different shapes by using suitable moulds, e.g., polyethene and polystyrene.
   (Plasticizers are high boiling esters or haloalkanes. These are added to I plastics to make them soft rubber like. …J
4. Thermosetting plastics These are normally semifluid substances with low molecular masses. When heated, they become hard and infusible due to the cross-linking between the polymer chains. As a result, they also become three dimensional in nature. A few common thermosetting polymers are bakelite, melamine-formaldehyde resin and urea formaldehyde resin.

Types of Polymerisation

1. Chain Growth Polymerisation or Addition Polymerisation

It involves formation of reactive intermediate such as free radical, a carbocation or a carbanion. For this polymerisation monomers used are unsaturated compounds like alkenes; alkadienes and their derivatives. Depending upon the nature of the reactive species involved. chain growth polymerisation occurs by the following mechanisms:

• Free radical addition polymerisation
• Cationic polymerisation
• Anionic polymerisation

(i) Free radical addition polymerisation The monomers used are generally monosubstituted alkenes. The most commonly used catalysts are benzoyl peroxide, hydrogen peroxide or t-butyl peroxide etc.

Mechanism The reaction involves the following steps

Step I Chain initiation step In this step, peroxide undergoes homolytic fission, e.g., benzoyl peroxide on heating produces phenyl initiator free radical.

Step II Chain propagation step The new free radical adds to another molecules of monomer to form a larger free radical.

Step III Chain termination step There are three ways of chain termination: Coupling reaction, disproportionation reaction, chain transfer reaction. One mode of termination of chain is shown as under:

(ii) Cationic polymerisation It involves formation of carbocation which are generated by Lewis acids (like BF₃, AICI₃, SnCI₄, etc.) and protonic acids such as H₂SO₄, HF, etc.

Higher the stability of carbocation intermediate, more is the reactivity of monomers towards cationic addition polymerisation. It involves the following steps:

Step I. Initiation Step

(iii) Anionic polymerisation It involves formation of a carbanion, Steps involved in this process are

Step I Initiation Strong bases act as initiator.

Step Growth Polymerisation

Condensation polymerisation which occurs in a stepwise manner with elimination of some smaller molecules like H₂O, NH₃, HCI, ROH, etc., is concerned with step growth polymerisation, e.g., adipic acid and hexamethylenediamine phenol and formaldehyde etc., undergo step Growth Polymerisation.

Distinction Between Chain Growth Polymerisation and Step Growth Polymerisation

Molecular Mass of Polymers

The growth of the polymer chain depends upon the availability of the monomers in the reaction. Thus, the polymer sample contains chain of varying lengths and hence, its molecular mass is always expressed as an average molecular mass.

Number-Average Molecular Mass M_n

If N₁ molecules have molecular mass M₁ each, N₂ molecules have molecular mass M₂ each, N₃ molecules have molecular mass M₃ each and so on,

then, M_n = Σ N_i M_i / Σ N_i

It is determined by osmotic pressure method.

It is determined by light scattering and ultracentrifugation method.

PoLydispersity Index

It is the ratio of the mass average molecular mass to the number average molecular mass

PDI = M_w / M_n

For natural polymers, PDI is usually equal to one which means that they are monodisperse. In other words, such polymers are more homogeneous. On the contrary, synthetic polymers generally have PDI > 1 which means that they are less homogeneous.

Polyolefins

These are obtained by the addition polymerisation of ethylene and its derivatives

1. Polythene

Polymer of ethylene or ethene.

(i) Low density polythene (LDP)

It is tough, flexible, transparent, chemically inert as well as poor conductor pf electricity. It has moderate tensile strength but good tearing strength.

It is used in the insulation of electricity carrying wires and manufacture of queeze bottles, toyes and flexible pipes.

(ii) High density polyethylene (HOP)

It has high density due to close packing. It is also chemically inert and more tougher and harder.

It is used for making containers, house wares, bottles, toyes, electric insulation etc.

2. Polystyrene (Styrone)

The monomers are styrene molecules. It is thermoplastic. It is used for making toys, radio and TV cabinets

3. Polyvinylchloride (PVC)

It is used for making rain coats, toys, electrical insulation. It is hard and resistant to heat and chemicals.

4. Polypropylene (PP)

It is obtained by polymerising propylene in the presence of Ziegler-Natta catalyst.

It is chemically inert and resistant to attack by corrosive reagent. It is used in making oil seals, gaskets and also for non-stick surface coated utensils.

6. Polyacrylonitrile

It is used as a substitute for wool in making commercial fibres as orIon or acrilan.

Polyamides

The polymers which contain an amide linkage in chain are known as pOlyamide, e.g., nylon-6, 6.

1. Nylon-66

It is obtained by the condensation of adipic acid and hexamethylenediamine with the elimination of water molecule

The polyamides are identified by numbers. These numbers refer to the number of carbon atoms in diamine and in the dibasic acid. As in the above case, the carbon atoms are 6 in each case, therefore the product is described as _nylon-66.

Properties and uses

Nylon-66 is a linear polymer and has very high tensile strength. It shows good resistance to abrasion. Nylon-66 is usually fabricated into sheets. It is used in bristles for brushes and in textile

2. Nylon-6

Nylon-6 is obtained by heating caprolactam with water at a high temperature.

Resins

1. Phenol-Formaldehyde Polymer

(Bakelite and Related Polymers)

These polymers are obtained by the condensation reaction of phenol with formaldehyde in the presence of either acid or a base catalyst. The reaction involves the formation of methylene bridge at ortho, para or both ortho and para positions. A linear or cross linked material is obtained depending upon the condition of reaction.

Uses

Bakelite is used for making combs, photograph records, electrical switches etc. Soft bakelites with low degree of polymerisation are used as binding glue for laminated wooden plants, in varnishes and lacquers.

2. Melamine-formaldehyde Resin

It is a copolymer formed by the polymerisation of melamine (which is a heterocyclic triamine) and formaldehyde as follows :

Properties and Uses

It is very hard and tough. It has assumed great importance these days particularly in making crockery. They do not break even when droped from a height.

3. Urea-formaldehyde Resin

4. Natural Rubber

Natural.rubber is a coiled linear 1, 4-polymer of isoprene.

In the polymer chain of natural rubber, the residual double bonds are located between C₂ and C₃ of the isoprene unit. All these double bonds have cis configuration, and thus natural rubber is cis-l,4-polyisoprene.

In the natural rubber, there is no polar substituent. The only intermolecular forces are van der Waals’ type. The cis-configuration gives the polymeric chain of natural rubber a coiled structure. As a result, it can be stretched by the application of a force. When the force is removed, the chain returns back to its original coiled shape.

Natural rubber is soft and sticky. It can be used only in the temperature range 10°C-50°C. At higher temperature, it becomes soft and at low temperature, it becomes brittle. It has higb water absorption capacity. It is attacked by oxidising agents and organic solvents. As such, it cannot be used very extensively for commercial puposes.

Vulcanisation of Rubber

The properties of natural rubber can be modified by introducing -S-S- polysulphide crosslinks in its structure. This process of introducing -S-S- crosslnks in the structure of natural rubber by heating with sulphur at 11O°C is called vulcanlsation of rubber.

Vulcanisatlon is carried out by adding sulphur (3-5%) and zinc oxide to the rubber, and then heating the object at about 110°Cfor about 20-30 minutes. Zinc oxide accelerates the rate of vulcanisation. Vulcanisation introduces polysulphide (-S-S-) bonds between the adjacent chains. These crosslinks tend to limit the motion of chains relative to each other.

5. Neoprene

Polymer formed by polymerisation of chloroprene is neoprene or synthetic rubber.

It is used for the manufacturing conveyers belts, gasket and hoses.

6. Buna-N

It is a copolymer of buta-I, 3-diene and acrylonitrile. It is formed as follows

Properties and Uses

It is insulator in nature and is used for making conveyor belts and printing rollers.

Polyesters

The polymers which contain an ester linkage are known as polyester, e.g., dacron.

1. Polymethylmethacrylate (PMMA)

It is prepared by the polymerisation of methylmethacrylate in the presence of suitable organic peroxide.

The polymer is known by several commercial names such as lucite, acrylite, plexiglass and perspex.

Properties and uses

It is a hard and transparent polymer and is quite resistant to the effect of light, heat and ageing. It is used, in the manufacture of unbreakable lights, protective coatings, dentures, and in making windows for aircrafts.

2. Glyptal

It is a polyester having crosslinks. It is a thermosetting plastic. It is obtained by condensation of ethylene glycol and phthalic acid or glycerol and phthalic acid.

When its solution in a suitable solvent is evaporated, it leaves a tough but non-flexible film. It is, therefore, used in the manufacture of paints and lacquers.

3. Terylene (Dacron)

It is a condensation product of ethylene glycol and terephthalic acid.

Polymerisation is carried out at 420 to 460 K in the presence of catalyst mixture of zinc acetate and antimony trioxide.

Properties and uses

Terylene is highly resistant to the action of chemical and biological agents. Its fibres are quite strong and durable. It can also be blended with wool or cotton to obtain fabrics of desired composition.

Terylene is used in the manufacture of a variety of clothes such as terycot, terywool and terysilk as a result of blending with other yerns. It is also used for preparing magnetic recording tapes, conveyer belts, aprons for industrial workers etc.

Biopolymers and Biodegradable Polymers

Synthetic polymers are mostly non-biodegradable i.e., it is very difficult to dispose off the polymeric waste, e.g., polythene bags.

Nature has provided us a variety of polymers which can be produced by the biological systems in plants and animals. These are called biopolymers, e.g., polysaccharides, proteins, nucleic acids, etc. In the biological system, these polymers decompose or hydrolyse in the Presence of different enzymes. This means that they are biodegradable.

Aliphatic polyesters are the common examples of biodegradable Polymers.

It is a copolymer of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid.

2. Nylon-2-Nylon-6

It is an alternating polyamide copolymer of glycine (H₂N-CH₂-COOH) and amino caproic acid [H₂N(CH₂) ₅COOH] and is biodegradable.

Some More Impotant Polymers

1. Saran is a copolymer of vinyl chloride and Isused for wrapping food materials.
2. ASS rubber is a copolymer of acrylonitrile, buta-1, 3-diene and styrene.
3. Bubble gum contains styrene butadiene rubber.
4. Epoxy resins are used In making adhesives such as araldite, etc. These are the copolymer of epichlorohydrin and bisphenol-A.
5. Thikol is another variety of synthetic rubber which is a copolymer of ethylene chloride and sodium tetrasulphide (Na₂S₄4).
6. Dynells a copolymer of vinyl chloride and acrylonitrile and is used for making human hair wigs.
7. Silk Is a thread like natural polymer which is obtained from cocoons of sllk worms. It is a natural polyamide fibre.
8. Thermocol Is a foamed plastic obtained by blowing air through molter polystyrene or polyurethane.
9. Superglue is a polymer of methyl α-cyanoacrylate and is obtained by anionic polymerisation of monomer.