CBSE Class – 6 | Science (Chemistry) | Chapter – 1 (Matter and its Nature) | Bharti Bhawan | NCERT

 Matter and its Nature

Class - VI                                        Science (Chemistry)

Matter :- Anything that occupies space and have mass is called matter.

Volume :- The space matter or anything occupies is called its volume.

Mass :- The amount of matter anything contains is called its mass.

Energy :- Anything that is not matter but has the capacity to do work is energy.

Ex.- Light, heat, electric, sound etc.

 Science Notes Class 6

1. Matter and it's Nature

2. Food

3. Classification of Material

4. Clothes and Fibre 

5. Separation of Substances

6. Study Of Changes 

Classification of Matter (State)

                                                                                                                       

Solid :- A solid has a fixed volume and a definite shape.

Liquid :- A liquid has a fixed volume but not a definite shape.

Gas :- A gas has neither a fixed volume nor a definite shape.

 

Inter conversion of State

 

The change in the state of matter from one to another is called inter conversion of state.

Melting :- The change in the state from solid to liquid is known as melting. (Solid – Liquid)

Melting Point :- The temperature at which solid melts.

Ex.- Melting point of :-

                          Ice                 -        0°C

                          Carbon          -        3500°C

                          Aluminium    -        660°C

                          Iron               -        1540°C

Freezing :- The change in the state from liquid to solid.

Freezing Point :- The temperature at which liquid changes into corresponding solid.

 

Note :- The freezing point of a liquid is the same as the melting point of the corresponding solid. Thus, the Freezing point of water and melting point of ice is 0°C

Boiling :-  The phenomenon of making bubbles in a  liquid after heating to a particular temperature.

Boiling Point :- The temperature at which liquid starts boiling.

Ex.- Boiling point of :-

                          Water           -        100°C

                          Acetone        -        56°C

                          Ethyl Alcohol -        78°C

                          Glycerine      -        290°C

 

Condensation :- The phenomenon of changing a matter from gaseous state to liquid is called condensation or liquefaction.

Vapour :- The substances that ordinarily exist in the solid or liquid state are called vapour in the vapour state. (Evaporate)

Ex.-                    Sulphur Vapour  (Solid)

                          Water Vapour (Liquid)

Sublimation :- The phenomenon of changing solid directly into gas without melting into liquid.

Ex.-                    Naphthalene,         Camphor

 Sorting Materials into Groups Class 6

Classification of Matter or Substances (Composition)

Pure Substances

 

Pure Substances:- A substance contains single substance is known as pure substance.

Element :- An element is a substance which cannot be broken down into simper substances by chemical means (chemical change).

Chemical change and Physical change

Metal * :-

  Properties:-       Hard Solid

                 Metallic lustre (shining)

                 Ductile (can bent)

                 Malleable (can be beaten or pressed into sheet)

                 Sonorous (give sound when heated)

                                   Good conductor of Heat and Electricity

 Note :- In metals Sodium (a soft solid) and Mercury (a liquid) are exceptions which are not solid.

Non-metal :-

     Properties:-    Exists in all three states

                                 Ex.- Solid (Sulphur, Phosphorus, Iodine)

                                         Liquid (Bromine)

                                         Gaseous (Hydrogen, Chlorine, Nitrogen)

                             Dull-looking (no lustre)

                             Brittle if solid (easily breakable)

                             Non-Sonorous

                                   Bad Conductor

• All living things is mainly contain substance called carbon.
• Chlorine used to kill germs in water.
• Iodine is used to heal wounds or sprains
• Sulphur is used to cure skin diseases

The name of third element is metalloid.

Compound :- A compound is a substance which is made up of combination of two or more elements in a fixed proportion.

           A compound is a substance that can be split or broken down into simpler substances by chemical means.

Impure Substances (Mixtures)

 

Impure Substance :- An impure substance or mixtures is a substance containing two or more substances (elements or compounds) in any proportion.

Ex.-                Air                      mixture of gases, moisture (water) and Carbon dioxide (compound)

                Natural Water          mixture of air and water

                Soft drinks                carbon dioxide, water, sweetening and flavoring agents

Alloy:- A Metal mixed with other metal or non metals.

Ex.-        Steel (iron, carbon, manganese)                                             

               Brass (copper, zinc)                                      

               Bronze (copper & tin)

 

Homogeneous Substances :-

 A substance is homogeneous if the different parts of it have the same property (behaviour) and composition.

(can mix easily but difficult to distinguish)

                Ex.-  All Elements (hydrogen, oxygen, gold) and Compounds (salt, sugar, water),

Alloy (solid solution), mixture of sugar and water

Heterogeneous Substances:-

A substance is heterogeneous if the different parts of it differ in property and composition.

(Easily distinguishable if mixed)

                Ex.- mixture of sand and husk

 History Notes Class 6

1. Studying the Past

2. Early Human - I

3. Early Human - II

5. The Age of Vedas

6.  Early Kingdoms

7. Growth of New Ideas

Building block of matter

 

Molecule :- Matter is made up of extremely small parts which can exist independently it is called molecules.

Ex.-

Atom     :- Small particle of a molecules is called atom. (not exist independently)

                Note :- A molecule of an element is made up of one kind.

                                A molecule of an compound is made up of two or more kinds / elements.

                Ex.-

Fundamental or Subatomic Particles

Atoms are further made up of small particles which is called fundamental or subatomic particles. They are:-

                1. Electrons                        2. Protons                           3. Neutrons

Charge :- Every fundamental particles have some electrical properties which is called charge.

·         It occurs in two opposite form :- positive (+ve) and negative (-ve). Same charges repel each other where as opposite chare attract each other.

·          

Properties of fundamentals or subatomic particles

 

Electrons :- Very light particle with negative electric charge

Protons:- Much heavier than electron with positive electric charge

Neutrons:- As heavy as a proton with no electric charge

·         At the center of the atom, there is a nucleus, which consist 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 round it

·         The nucleus is positively charged due to the protons. But the same number of electrons (as protons) revolve round the nucleus and balance the positive charge of the nucleus. So the atom is electrically neutral.

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