Sunday, 31 August 2014

Structure of atom: DALTON'S ATOMIC THEORY and its DRAWBACKS


Dalton put forward his atomic theory of matter in 1808. The various postulates of Dalton's atomic theory are as under:

1)         Atoms are indivisible i.e. they can’t be divided further.
2)         All matter around us is made up of particles called "atom".
3)         Atoms are of various kinds. There are as many kinds of atoms as are elements.
4)         Atoms present in a given element have same mass same size & same chemical properties.
5)         Atoms present in different elements have different mass different size & different chemical properties.
6)         During chemical combination atoms of different elements combine together in small whole numbers               to form compounds.
7)         Atoms of same elements can also combine in more than one ratio to form more than one compound.
8)         Atom can neither be created nor be destroyed.



1)         According to Dalton atom is indivisible but now a days atom can further be divided into  three parts namely "electrons" , "protons" & "neutrons" respectively.
2)         He suggested that atoms of same element are same in every aspect but it has been proved that atoms of same element have slightly different masses.
3)         He also suggested that atoms of different elements are different in every aspect but now a days we know that the atoms of different elements can also have same mass.
4)         He also explained that during a chemical reaction atoms of different elements combine in small whole numbers but it has been proved that they only only combine in small whole numbers but they can also combine in large whole numbers.

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