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# How is valency of an element found? Find the valency of chlorine, sulphur, silicon and magnesium.

Discussion in 'CBSE Class 9 Chemistry Help' started by phani, Jan 8, 2012.

1. The electrons present in the outermost shell of an atom of an element are known as valence electrons. Valency is the combining capacity of an element. If the number of valence electrons of an atom of an element is less than or equal to 4, then the valency of the element is equal to the number of electrons in the outermost shell. On the other hand, if the number of electrons in the outermost shell of the atom of an element is greater than 4, then the valency of that element is determined by subtracting the number of outermost shell electrons from 8.
The distribution of electrons, i.e., the electronic configurations of the given elements are
Chlorine—2, 8, 7
Sulphur—2, 8, 6
Sihcon—2, 8, 4
Magnesium—2, 8, 2
Therefore, the number of electrons in the outermost shell of chlorine, sulphur, silicon and
magnesium atoms are 7, 6, 4 and 2 respectively. Thus, the valency of chlorine = 8 — 7 =
The valency of sulphur = 8 — 6 = 2
The valency of silicon = 4
The valency of magnesium = 2