Theory of Hydrogen Atom

With the discovery of the particle of atom by Gold stein, Thomson and Chadwick the need of atomic model had a great importance. J.J. Thomson suggested the "plum pudding" model. The atom consisted of subatomic particles called protons and electrons. In this model the electrons and protons are uniformly mixed throughout the atom. However, it was not clear how these protons and electrons were arranged within the atom. I like to share this Angular Velocity Formula with you all through my article.

Rutherford reasoned that if Thom son's model was correct then the mass of the atom was spread out throughout the atom. Then, if he shot high velocity alpha particles (helium nuclei) at an atom then there would be very little to deflect the alpha particles. He decided to test this with a thin film of gold atoms. As expected, most alpha particles went right through the gold foil but to his amazement a few alpha particles rebounded almost directly backwards. Rutherford was forced to discard the Plum Pudding model and reasoned that the only way the alpha particles could be deflected backwards was if most of the mass in an atom was concentrated in a nucleus. He thus developed the planetary model of the atom which put all the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun. Electrons move round the nucleus in an elliptical orbit. So his model is named as planetary model of atom. He was unable explain about the states of an atoms and could not explain why electron would not lose or gain energy as long as it moves in a specific orbit his proposal was a failure. After the failure of Rutherford elliptical atomic model of hydrogen, Neil Bohr introduced his circular model of Hydrogen atom.

Bohr hydrogen atom


1) Electron moves around the nucleus in a circular orbit. The centrifugal force of the electron moving in the circular orbit is balanced by the coulombs force of attraction between the electron and the nucleus.

mV^2 /R = ke^2 /R^2

2)   For the electron moving in an orbit, the orbital angular momentum is equal to integral multiple of h /2 p

mV R = n h / 2 p

3) As long as the electron moves in a particular orbit it neither loses nor gains energy. This state is called stationary state. The total energy of a revolving electron in one of the stationary state remains constant.

4) When an electron jumps from one orbit to the other, either energy is released or absorbed. When an electron jumps from higher stationary state to a lower stationary state, energy is liberated. The difference in the energy states is proportional to the frequency of the emission of radiation.

E2 – E1 = h v

Having problem with Alternate Current keep reading my upcoming posts, i will try to help you.

Short coming of Bohr Hydrogen atomic model


1) The theory could not explain the spectra of atoms complex than hydrogen.

2) The theory could explain the distribution and arrangement of electrons in an orbit in the atom.

3) The theory could not explain the fine structure of atoms.

4) The theory could not explain splitting of spectral lines due to electrical (stark effect) and magnetic field (Zeeeman effect).