Question

What changes have taken place. In the dalton's atomic theory in modern days

Answer 1

Daltons Atomic Theory (Postulates)
• atom is an indivisible particle.
• atoms of same element are similar in all properties.
• atoms of different elements differ in all properties
• atoms of different element combine in a fixed simple whole number ratio.
• the smallest particle taking part in a chemical reaction is an atom.

MODERN ATOMIC THEORY (Postulates):
• atom contains of subatomic particles which may be charged- electron and proton and can be neutral- neutron.
• atoms of same element are not similar in all aspects (isotopes)
• atoms of different elements do not differ in all aspects(isobars)
• atoms of different elements combine in a fixed but not in a simple ratio
• atom is the smallest particle that takes part in a chemical reaction but it may or may not have independent existence
• atom of one element can change onto atoms of other element by transmutations (nuclear reactions)

Answer 2

According to modern theory
Atom is divisible
Atom is independent to react in a chemical reaction