Atoms ions and molecule

1.   By Greek philosophers Leukippos and 

      Democritus :

  Atom is the smallest particle that cannot be 

      subdivided anymore. 

2.    Aristotle:

       Matter can be subdivided again and again

       without any limit.

3. John Dalton

    Dalton’s theory of atom can be simplified

    as follows:

1.Every matter is composed of the smallest particles   called atom.

2.An atom cannot be subdivided into smaller particle having the  same 

   characteristics.

3.Atoms certain element have identical characteristic   and mass. Different elements     

   have different mass of atoms.

4.Compound is composed of two or more difference atoms.

5.Chemical reaction is the combination and separation of atom of element or 

   compound in a reaction.

weakness

1.It can’t explain the electricity of matter

2.It can’t explain the combining power of atoms