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Principle of distributing electrons
CHEMISTRY - Secondary 2
In This part we will study:
 Hund's rule :
Hund's rule: States that no electron pairing takes place in a given sublevel until each orbital contains one electron.
• Rules of filling the energy sublevels with electrons, according to Hund's rule:
Notes
 The spin of single electrons in the same sublevel orbitals is in the same direction.
Because this state gives the atom the maximum stability.
 The electron prefers to occupy an orbital alone in the same sublevel rather than pairing with another one in the same orbital.
Because when two electrons are paired in one orbital, (in spite of their opposite spins), there must be a repulsive force that decreases the stability of the atom (increasing its energy).
 The electron prefers pairing with another one in an orbital in the same sublevel rather than transferring to the higher energy sublevel.
Because the required energy to overcome the repulsive force between the two paired electrons is less than that is required for transferring the electron to a higher sublevel.

Best wishes to you
Mr.Ahmed Elbasha

كيمياء الصف الثاني الثانوي لغات - الفصل الدراسي الاول
شرح كيمياء لغات تانية ثانوي - مستر احمد الباشا