شرح درس
Principle of distributing electrons
CHEMISTRY - Secondary 2
In This part we will study:
Principle of distributing electrons
There are some important rules, which must be considered in distributing electrons
in the atom. These rules are:
 Pauli's exclusion principle.
 Aufbau (building-up) principle.
 Hund's rule.
Pauli's exclusion principle: States that it is impossible for two electrons in the same atom to have the same four quantum numbers.
Example
Write the possible values of the four quantum number for each of the following:
(a) An electron in 2p-sublevel.
(b)The first electron in 4d-sublevel.
(c) The second electron in 1s-sublevel.

Best wishes to you
Mr.Ahmed Elbasha

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