__Atomic Structure__

__Atomic Structure__

__Atom:__

__Atom:__

In Greek Atom means not divided. In 1803 **john Dalton** made a famous theory atomic theory according to this theory “matter is made up of tiny particles called atoms.” But in 1897 Sir **J.J. Thomson** proved experimentally that atoms are made of charged particles called electrons. And in the beginning of 20^{th} century many scientists like **Lord Rutherford, E. Goldstein** proved that atom is not a smallest particle but is made up of electron, protons and neutrons.

**De-Broglie’s equation:**

According to the plank’s photon of light having energy E and frequency n.

Then E = hn …………………………………………….(1)

According to Einstein Mass, energy relation is

E = mc

^{2}………………………………………(2)Where c is velocity of light

Combining both above equations (1) & (2) we get

hn = mc

^{2}^{}

Then

Or

Or

This equation for photon, when we put v in place of velocity of light c it becomes.

This equation is known as de-Broglie equation.

Since h is constant and p is momentum (mv) of particle.

Then

de-Broglie equation is applicable to electron, proton, neutron, atoms, molecules etc. and is also applicable to calculate wavelength of moving material particles if velocity is known.