Dalton atomic theory and its modifications.

John Dalton was an English school teacher and a researcher who gave the first scientific theory of matter based on his experiment and observations,He studied how gases combine,react,move with change in temperature and pressure and through his research he developed his idea called the Dalton atomic theory in 1803.
Postulates of Dalton atomic theory and modifications
1.All the matter is made of tiny indivisible particles known as atoms.
Modification:after the discovery of proton,elelctron and neutron the idea of indivisibility of atom was modified.
2.Atoms cannot be created or destroyed.
Modification:This statement is still applicable for ordinary chemical reactions but in nuclear reactions atoms can be created or destroyed.
3.Atoms of a given element are identical in mass,shape,size and chemical properties.
Modifications:After the discovery of isotopes this statement was rejected since isotopes are atoms of same element having same atomic number but different mass number,that means atoms of same element can have different mass
4.Atoms of different elements have different mass and chemical composition.
Modification:Atoms of different atoms can have same mass no that means same mass even though they are atoms of different elements.
5 Atoms combine in the ratio of simple whole number ratio to form compound.
Modification:It is not necessary that atoms combine in simple whole number ratio for example in organic compounds have large whole no ratios,sucrose is one of the example having formula C12H22O11
6. The relative number and kind of atoms are same in a given compound.
Modification:There are compounds which can have different composition of atoms in a given compound
You can also see the video about the same for simple expalnation!!!