Johan Dalton's atomic theory

Johan Dalton and atomic theory:

In 1808 Johan Dalton developed the atomic model. The three main features of Johan Dalton postulation are:
1- Any element is composed of tiny particles he named them atoms.
The atom is the smallest particles of an element that retains the properties of the element. All atoms of a given element have the same chemical properties. Atoms of different elements show different properties.

2- Atoms of any element do not disappear or change during chemical reaction, atoms only moves from one substance to another.
3- Compounds formed due to the combination of more than one element. The number of atoms in each compound are definite and constant. Example water forms due to the combining of two hydrogen atoms with one oxygen atom.