Classification of Matter

Matter is categorised based on its chemical composition into two broad groups:

1. Pure Substances have a definite, fixed chemical composition. They are further divided into:

• Elements — the simplest form of matter; cannot be broken down further by ordinary chemical means. Example: pure silver.

• Compounds — formed when two or more elements chemically combine in a fixed ratio. Example: common salt (NaCl).

2. Mixtures have no fixed composition and therefore no definite properties. They are divided into:

• Homogeneous Mixtures — constituents are uniformly distributed throughout the sample. Example: vinegar.

• Heterogeneous Mixtures — constituents are not uniformly distributed. Example: tomato sauce.

Quick memory trick:

Pure → Fixed composition. Mixture → Variable composition.