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Theory of Atoms.
Greek philosopher Democritus first suggested that all substances consisted of tiny indestructible particles called atoms. -
John Dalton's Atomic Theory
John Dalton's atomic theory proposed that:
-All matter consisted of tiny particles called atoms.
-Atoms could not be divided into smaller particles.
-Atoms of the same element were alike.
-Atoms combined in simple whole number ratios. -
Sir J.J Thomson
English scientist Sir J.J. Thomson explained that the atom contained negatively charged particles called electrons. is model suggested that atoms were positively charged spheres with negatively charged electrons embedded in them like the fruit in a plum pudding. -
Lord Rutherford.
Proposed that the atom consisted mostly of empty space with a dense nucleus containing positively charged protons in the centre. -
Neil Bohr.
Suggested that electrons orbit the nucleus at different energy levels. -
Sir James Chadwick.
Discovered that the nucleus contained particles called neutrons.