Class 6th Chapterwise Notes

1. Anything that occupies space and has mass is called matter.
2. The space anything occupies is called its volume.
3. The amount of matter anything contains is called its mass.
4. Anything that does not matter but has the capacity to do work is energy.
5. Matter exists in three states-solid, liquid and gaseous.
6. The change in the state of matter from one to another is called interconversion of state.
7. On the basis of composition, the matter is classified as follows. Matter Pure Impure (or mixture) Elements Compounds or Metals Nonmetals •
8. An element is a substance that cannot be broken down into simpler substances by chemical means.
9. A compound is a substance that can be split or broken down into simpler substances by chemical means.
10. A substance is homogeneous if the different parts of it have the same property (behaviour) and composition.
11. A substance is heterogeneous if the different parts of it differ in property and composition.
12. The matter is made up of extremely small parts, called molecules, that can exist independently. composition.
13. Molecules are made up of still smaller parts, called atoms, which do not generally exist independently.
14. A molecule of an element is made up of atoms of only one kind.
15. A molecule of a compound is made up of atoms of two or more kinds, i.e., two or more elements.
16. An atom is made up of still smaller particles-electrons, protons and neutrons-called fundamental er subatomic particles.
17. At the centre of the atom, there is a nucleus, which consists of protons and neutrons (except the nucleus of hydrogen, which has only a proton and no neutrons). And at a distance from the nucleus, there are electrons revolving around it.
18. An electron is a negatively charged particle and a proton is a positively charged particle. A neutron carries no electrical charge.
19. The nucleus is positively charged due to the protons. But the same number of electrons (as protons) o round the nucleus and balance the positive charge of the nucleus. So the atom is electrically neutral.

1. Every organism needs food (a) to get energy, (b) for growth, repair and maintenance of the body, and to fight diseases.
2. We get our food from plants and animals, Cereals, pulses, vegetables, fruit, spices, oil, sugar and beverages come from plants. In grams or cereals, the fruit and seed are fused together.
3. Animals give us meat, milk, eggs and honey. The practice of bee-keeping is called apiculture.
4. Diet is the food we generally eat. A balanced diet contains all the nutrients required by the body in the right proportion.
5. Our body needs five groups of nutrients-carbohydrates, fats, proteins, vitamins and minerals Carbohydrates and fats are called energy-giving food. Proteins are tissue-building food, and vitamins and minerals are protective food.
6. Sugars and starch are carbohydrates. They contain carbon, oxygen and hydrogen. Starch contains more energy than do sugars. Excess carbohydrates are stored as fat. Accumulation of fat can cause obesity.
7. Fats contain carbon, hydrogen and oxygen. They produce more energy than carbohydrates do but are more difficult to digest. They act as an energy bank, protect the body from cold and cushion internal organs.
8. Proteins contain nitrogen, carbon, hydrogen and oxygen. They are needed to build and repair tissues. Hair, skin, nails, and muscles are made up of proteins.
9. Vitamins and minerals are needed for the proper growth and functioning of the body. Some deficiency diseases due to the lack of vitamins and minerals in the body are as follows.
10. Vitamin D-rickets Vitamin A-night blindness Vitamin B,-beriberi Vitamin B,-pellagra Vitamin B -anaemia Vitamin C-scurvy Iodine-goitre Calcium-weak bones and iron Phosphorus-weak bones and teeth.

1. Grouping similar things together is called classification.
2. Materials are classified on the basis of their properties.
3. Materials which shine are said to be lustrous and those which do not are sald to be nonlustrous.
4. - On the basis of smoothness of surface, materials are grouped as smooth and rough.
5. • On the basis of the ability to allow light to pass through, materials can be grouped as transparent, translucent and opaque.
6. A solid material is said to be ductile if it can be bent or its shape can be changed without breaking it.
7. Such materials can be drawn into wires. The solid material is said to be malleable if it can be beaten or pressed into sheets or foils. A solid material that breaks on being bent, beaten or pressed is called brittle.
8. A solution is a homogeneous mixture.
9. Materials that dissolve in water are said to be soluble in water, and those which do not are said to be insoluble in water.

1. Fabrics are made from fibres. Fibres are spun into yarn and yarn is woven into cloth.
2. Fibres can be natural or artificial (also called synthetic).
3. Natural fibres are derived from plants or animals.
4. Cotton, flax and jute are examples of plant fibres. Wool and silk are animal fibres.
5. Rayon, nylon, polyester and Terylene are synthetic fibres.
6. The Indians were the first to cultivate cotton and to make cloth from it. Cotton is obtained from bolls left behind after the petals of the cotton flower fall off.
7. Flax and jute fibres are obtained from the stems of the plants.
8. The cotton cloth absorbs water efficiently and burns at a moderate speed.

1. A mixture is a substance that can be separated into two or more pure substances by simple physical means.
2. The constituents of solid mixtures are separated by hand-picking. winnowing, sieving, magnetic separation, and dissolution and evaporation (or crystallisation).
3. The constituents of solid-liquid heterogeneous mixtures are separated by sedimentation and decantation, filtration, and distillation. Distillation is used to separate the constituents of solid-liquid homogeneous mixtures too.
4. A separating funnel is used to separate immiscible liquids.

To study a change systematically, one should look for answers to the following questions.
1. Is there a change in the shape, size or colour of the material?
2. Is the change slow or fast?
3. Can the opposite change be brought about?
4. Are any new substances formed as a result of the change?
5. Is heat given out or taken in during the change?
• Changes are classified into physical and chemical changes.
• A change in which no new substances are formed and which can be reversed by reversing the conditions • A change in is called a physical change.
• A change in which new substances are formed and which cannot be reversed by reversing the condition is called a chemical change. A chemical change is also called a chemical reaction.
• Changes can be brought about by one or more of the following methods.
1. Heating or cooling
2. Increasing or decreasing pressure
3. Mixing