Wednesday, May 6, 2020

Different theories of atomic structure part 1

As we all know that the atom is the smallest  particle of element. Size of the atom are very small less then 100 picometers. Atom consist of three sub atomic particle named as electron (negatively charged) proton (positively charged) neutron (chargeless). There are different theories to explain the structure of atom and arrangement of sub atomic particle in atom. At first the greek philosopher Democritus believed that atoms were indivisible but his ideas didn't agree with later scientific theory.
Dalton Atomic model
John Dalton was a British School teacher published theory of atom in 1808.This was the first modern atomic theory his theory of atomic structure was based on the law of chemical combination
The major postulates of Dalton's atomic theory
1.     Every matter composed of small particles called atoms.
2.     Atoms of the same element are similar in shape and mass, but differ from the atoms of other elements.
3.     Atoms can nither be created or nor be destroyed.
4.     Atoms of different element may combine with each other in a fixed,simple,        whole number ratios to form compound atoms.
5.     The atom is the smallest unit of element and can take part in a chemical reaction.
Drawabacks of Dalton atomic model
1.     This theory didn’t explain about the sub atomic particle electron, proton and neutron.
2.     This theory fail to explain about the existence of allotropes.
3.     Fail to explain about the isobars.Fail to explain about isotopes.
Thomsom atomic model
According to thomsom atomic model an atom is a positive sphere in which electorn are embedded like seeds in watermelon. Hence this theory is also called thomsom watermelon atomic model This model had no theoretical and practical justification and was soon discard 
Drawbacks of Thomsom atomic model
. This theory didn't explain about the positively charged particle in atom.
.This theory didn't explain about the stability of atom
.This theory didn't tell us anything about the nucleus of atom.


Different theories of atomic structure part 1

As we all know that the atom is the smallest  particle of element. Size of the atom are very small less then 100 picometers. Atom consist ...