الباب الاول للغات مراجعةشرح د/ عاطف خليفة

[عاطف خليفة]

* (2) Bohr’s atomic model

Bohr’s Postulates

1- He adopted some of Rutherford’s postulates

2- He added that; the electrons orbit the nucleus without emission or absorption any energy.

3- The electrons orbit only in definite allowed energy level

4- The energy of any level increases as its radius increases.

5- Each energy level is expressed by a whole number (Principal quantum number) - which is 1 for level K-, 2 for level L, ..

6- When an electron acquires an amount of energy (quantum) by heating or electric discharge, it becomes excited and it jumps to higher energy level , then it returns to its original level losing the temporarily absorbed energy in the form of radiant.

7- Many atoms absorb different amount of energies and others radiate energies at the same time

* Notes

1. Quantum : The amount of energy absorbed or emitted when an electron jumps from one level to another

2. The amount of energies needed to transfer the electron through different energy levels are not equal.

3. The electron can’t orbit in the distance between energy levels

4. There is no parts of quantum

* Bohr’s model succeeded in

(1) Explaining the hydrogen atom spectrum

(2) Introducing the idea of quantized energy states for electron
(3) Reconciliation between Rutherford and Maxwell theories.

* Bohr’s model failed in

(1) The model failed to explain the spectrum of any other element expect hydrogen.

(2) It didn’t consider the wave properties of the electron

(3) It is impossible to determine precisely both the location and the
speed of an electron at the same time

(4) It considered that the atom is planar while it has three dimensional coordinates