Postulate of Bohr Theory

Postulate of Bohr Theory

The fact that hydrogen spectrum of Balmer equation was represented successfully, but there were no theoretical proved for it. Therefore, Niels Bohr in 1914 provide a theory that explain the genesis of it spectrum. The theory provided by Niels Bohr give a new shape to entirely concept of atomic structure, Niels Bohr model of hydrogen atom stand on four postulates label as, 1^st, 2^nd, 3^rd, and 4^th postulates.

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1^st Postulate: Atomic hydrogen, made up central nucleus, the nucleus consist of Proton with positive +e charge and electron with negative –e charge. The electron are in circular movement, orbiting radius r round the nucleus.

Equation involved in the circular movement could be trace to Coulombs law; according to the low force of attraction between electron and nucleus is

F = k and k = , = represent vacuum permittivity, and Z = 1 represent number of hydrogen atoms.

The above force equalized a centrifugal force, a force that keep electron moving round a circle, mv²/r, where m = mass of the electron and v = velocity.

= k =

ATOMIC BOHR’S MODEL

Based on our discussion so far, it shown that electron is on motion, for an electron to be on motion, there must a certain form of energy that keep the electron moving, the energy that keep the electron on motion is called kinetic energy. Below is the formula of kinetic energy;

Kinetic energy = mv² =

Take note of the following;

M_e = mass of an electron is 9.109 x 10 ^{– 31}kg

1eV = 1.602 x 10 ^{– 19}J

C = speed of light is 3.0 x 10 ⁸ms ^{– 1}

e = electrical charge quantity is 1.602 x 10 ^{– 19}C

R = Rydbergs constant is 1.097 x 10 ⁷m ^{– 1}

= permittivity of the vacuum is 8.854 x 10 ^{– 12} C ² N ^{– 1}m ^{– 2}

h = plank constant is 6.626 x 10 ^{– 34}Js

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