The quest to find indivisible particles of matter started as early as 450 BC with the Greek philosopher Democritus. He wondered what would happen if one kept on cutting an apple into smaller pieces. He named those final pieces which could not be cut anymore ‘atomos’. The modern name atom comes from this.
British Chemist John Dalton revived the ideas of Democritus in the1800s. He developed Dalton’s atomic theory from his research. It states:
a) All substances are made of atoms.
b) Atoms are the smallest particles of matter which cannot be divided further.
c) Atoms can neither be created nor be destroyed.
d) All the atoms of element are alike and have the same mass. Atoms of different elements have different masses.
e) Atoms join together to form compounds and a given compound always consists of the same kinds of atoms in the same ratio.
Dalton’s theory was accepted worldwide. However, Dalton’s idea that atoms are the smallest particle was disproved with the discovery of protons, neutrons and electrons.
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