Evolution of atomic theories

Democritus

401

assumed the existence of the atom as an indivisible part of matter, and also ruled that there were different types of atoms that combined of forms and with different ordinations formed the various existing substances. It also assumed that when wood burned or iron oxidized, the particles that formed both wood and iron were rearranged to become ashes and rust respectively.

Dalton

1808

Also known as "billiard ball model" theory was based on a series of scientific laboratory experiences.
Dalton's atomic theory is based on the following statements:
- Matter is made up of atoms, which are indivisible and indestructible particles.
- All the atoms of the same chemical element are equal in mass and properties and different from the atoms of any other element.
- Compounds are formed by combinations of atoms of different elements.