MODELS OF THE ATOM

CONTENT

1. The Concept of Atom
2. J.J. Thompson’s Plum Pudding Model of the Atom
3. Rutherford’s Nuclear Atomic Model
4. Neil Bohr’s Postulate
5. Electron-cloud Model
6. Solved Examples

The Concept of the Atom

The word ‘atom’ was derived from the Greek word ‘atomos’ means indivisible. It was first used by the Greek philosopher Democritus to refer to the tiny or minutest part of all substance that cannot be further cut or divided. Although this idea had been since the late 5^th century/early 4^th century BC, it was until 1808 that the actual existence of atom was first proved by the English Chemist John Dalton when he put forward his famous John Dalton Atomic Theory.

However, the John Dalton Atomic Theory did not give insight into what the structure of an atom is. John Dalton answered the question, ‘does an atom exist?’ with proves but did not answer the question ‘what does an atom look like?’

Atomic Models

These were some of the attempt by scientists to answer the question – ‘what does an atom look like?’.