Question

(a) Define valency of an element. What valency will be shown by an element having atomic number 14?
(b) What is the relation between the valency of an element and the number of valence electrons in its atoms? Explain with examples.

Answer 1

(a) Valency of an element can be defined as the number of electrons present in the valence shell that is/are available for bonding.
Electronic configuration of the element having atomic number 14 is 2, 8, 4.
As this element has 4 electrons in its valence shell it's not possible to lose 4 electrons, so valency of this element is 4.

(b) Valency of an element is the number of electrons available for bond formation while valence electrons are electrons available in the outer most shell of the atoms.

For eg.,
Electronic configuration of chlorine is 2, 8, 7.
Valence electrons = 7
Valency of chlorine = 1

Electronic configuration of aluminium is 2, 8, 3.
Valence electrons = 3
Valency of aluminium = 3