jan 24, 1808 - John Dalton (1810 AD)
Description:
After over a thousand years of going unnoticed after the death of Democritus in the Classical Age, Atomic Theory is revisited by British scientist John Dalton. Unlike Democritus, who believed that there was an element for everything, Dalton believed in multiple elements consisting of one atom, which are the exact same for the same element. These elements could also bond to form compounds. He also first postulated the law of conservation of matter.
The postulates of Dalton's atomic theory are as follows:
All matter consists of very, very small particles called atoms.
An atom cannot be divided further, it is indivisible.
Atoms cannot be created or destroyed (conservation of matter).
All atoms of the same element are identical in all respects, such as mass, reactivity, etc,.
Atoms of different elements have different chemical properties and masses.
Atoms of different elements can combine in small whole number ratios to form compounds.
In a given compound, the relative number and types of atoms are constant.
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History of atomic theory
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