The term ‘atom’ comes from two Greek words meaning ‘not’and ‘cut’. It is the smallest portion of an element which cannot be cut into still smaller portions. All material bodies, WHETHER elements or compounds, are fundamentally granular in structure, i.e., made up of discrete particles SEPARATED by interspaces.

These ultimate constituents of matter are called atoms. They can take part in chemical reactions. This was the ancient CONCEPT of atomism of John Dalton (1808). Modern scientific researchers have, however, decided in favour of the atomic theory of matter, though the ancient concept of atoms as the ultimate and indivisible units of matter has been modified.

The concept of atomism is supported by the following FACTS:

1. Compressibility of matter
2. The phenomena of diffusion, osmosis, Brownian movement, solubility 
3. The regular forms of CRYSTALS governed by definite simple laws
4. The law of multiple proportions
5. The periodic law among elements.

The term ‘atom’ comes from two Greek words meaning ‘not’and ‘cut’. It is the smallest portion of an element which cannot be cut into still smaller portions. All material bodies, whether elements or compounds, are fundamentally granular in structure, i.e., made up of discrete particles separated by interspaces.

These ultimate constituents of matter are called atoms. They can take part in chemical reactions. This was the ancient concept of atomism of John Dalton (1808). Modern scientific researchers have, however, decided in favour of the atomic theory of matter, though the ancient concept of atoms as the ultimate and indivisible units of matter has been modified.

The concept of atomism is supported by the following facts: