Some Basic Concepts of Chemistry


Some Important Points and Terms of the Chapter

1. Anything which has mass and occupies space is called matter. 2. Matters exist in three physical states viz. solid, liquid and gas. 3. In solids, these particles are held very close to each other in an orderly fashion and there is not much freedom of movement. In liquids, the particles are close to each other but they can move around. However, in gases, the particles are far apart as compared to those present in solid or liquid states and their movement is easy and fast. 4. Solids have definite volume and definite shape. 5. Liquids have definite volume but not the definite shape. They take the shape of the container in which they are placed. 6. Gases have neither definite volume nor definite shape. They completely occupy the container in which they are placed. 7. A mixture contains two or more substances present in it (in any ratio) which are called its components. 8. A mixture may be homogeneous or heterogeneous. 9. In a homogeneous mixture, the components completely mix with each other and its composition is uniform throughout. Sugar solution and air are thus, the examples of homogeneous mixtures. 10. In heterogeneous mixtures, the composition is not uniform throughout and sometimes the different components can be observed. For example, the mixtures of salt and sugar, grains and pulses along with some dirt (often stone) pieces, are heterogeneous mixtures.. 11. The components of a mixture can be separated by using physical methods such as simple hand picking, filtration, crystallization, distillation etc. 12. Pure substances have characteristics different from the mixtures. They have fixed composition, Copper, silver, gold, water, glucose are some examples of pure substances.

Glucose contains carbon, hydrogen and oxygen in a fixed ratio and thus, like all other pure substances has a fixed composition. Also, the constituents of pure substances cannot be separated by simple...