Question

State bohr's postulates for explaining the spectrum of hydrogen atoms.

Answer 1

Bohr’s Postulates or Bohr’s Model of the Hydrogen Atom

1. An atom has a number of stable orbits in which an electron can reside without the emission of radiant energy. Each orbit corresponds, to a certain energy level.

2. An electron may jump spontaneously from one orbit (energy level E1) to the other orbit (energy level E2) (E2 > E1); then the energy change AE in the electron jump is given by Planck’s equation

∆E = E2-E1 = hv

 

 

Where h = Planck’s constant.

And v = frequency of light emitted.

 

3. The motion of an electron in a circular orbit is restricted in such a manner that its angular momentum is an integral multiple of h/2π, Thus

mvr = nh/2π, where m = mass of the electron

v = velocity of the electron

r = radius of the orbit an

n = an integer called principal quantum number of the electron.

4. A special surface around nucleus which contained orbits of equal energy and radius was called shell. These shells are numbered from inside to outwards as 1, 2, 3, 4 etc. and called K, L, M, N etc., respectively.