Question

Define valency by taking the examples of silicon and oxygen.

Answer 1

Valency: The valency of an element is the combining capacity of the atoms of the element with atoms of the same or different elements. The combining capacity is explained in terms of their tendency to attain a fully - filled outermost shell (stable octet or duplet).

• The valency of an element is determined by the number of valence electrons in an atom of the element.
  The valency of an element = number of valence electrons (when the number of valence electrons is from 1 to 4).
• For example, a silicon atom contains 4 valence electrons so the valency of a silicon atom is four.
  The valency of an element = 8– the number of valence electrons. (when the number of valence electrons is more than 4)
• for example, Oxygen contains 6 valence electrons so the valency of oxygen is 8-6=2.