1)Atoms are consider ed as divisible particles
2)Atoms of the same element may not be similar in all respects.(eg:Isotopes)
3)Atoms of different elements may be similar in some respects(eg:Isobars)
4)Atoms are the smallest particle which takes part in chemical reactions
5)The ratio of atoms in a molecule may be fixed and integral but may not be simple.(eg:C12H22O11 is not a simple ratio)(Sucrose)
6)Atoms of one element can be changed to atoms of another elements by transmutation.
7)The mass of an atom can be converted into energy.This is in accordance with Einstein's equation E=mc^2