Matter: Definition and Overview.

Hello everyone, you all are familiar with the term matter.

Anything which has mass and occupies space is called matter.

Everything around us has mass and they occupy space.
 Also, you are aware that matter can exist in three physical states viz. Solid, Liquid, Gas. 

Solid: these particles are held very close to each other in an orderly fashion and there is not much freedom of movement.

Liquid: the particles are close to each other but they can move around.

Gas: the particles are far apart as compared to those present in solid or liquid states and their movement is easy and fast.

Characteristics of the given matter:

(i) Solids have definite volume and definite shape.
(ii) Liquids have definite volume but not a definite shape. They take shape of the vessel in which they are placed.
(iii) Gases have neither definite volume nor definite shape. They completely occupy the vessel in which they are placed

Properties of matter:

There are some changes during which no new substances are formed whereas during some other changes new substances are formed. Therefore on this basis, we can classify all the changes into two groups (1)Physical Changes (2)Chemical Changes.

(1)Physical Changes :

A physical change in which the composition of a substance is not affected, i.e. no new substance is formed. e.g. Inter-conversion of states is a physical change because these changes occur without a change  in composition and no change in the chemical nature of the substance.

Evaporation, distillation, sublimation, condensation and crystallization are examples of physical changes.
The blue colour of copper sulfate crystal disappears when it is heated strongly because on heating water of crystallization of crystal is lost. It regains its blue colour when moistened with a drop of water.
It is an example of a physical change.

Some facts about the physical changes are

- Physical changes are temporary and reversible.

- Composition of the constituent of the matter remains the same during physical change i.e. constituent particles of matter does not change.

- Physical changes are due to the change in physical properties like density, volume, the state temporarily.

(2)Chemical Changes:

These changes result in the formation of new substances. In a chemical change, the composition and molecular structure of the substance undergoing changes are considered.
Rusting is a chemical change that can't be reversed back any physical process. As we eat food, the digestion of food starts from the mouth and during this process, many chemical changes take place in the stomach.

Similarly, the burning of any substance is a chemical change.

Note: 

• Burning a candle is an example of both physical and chemical changes. 
• Ozone is decomposed to oxygen in the presence of ultraviolet rays, It is an example of chemical change.

Some facts about the chemical changes are

- During chemical changes, the composition of the substance changes due to change in constituent particles of a substance.

- Identity of the substance is lost during a chemical change.

- Energy is absorbed or released during a chemical change.

-Chemical change is permanent and irreversible.

Classifications of Matter.