How do you calculate valency of an element from its electronic configuration ?

How do you calculate valency of an element from its electronic configuration ?

Ans. Electronic configuration tells about the valence electrons. If the number of valence electrons are 1, 2 or 3, then such elements will donate 1, 2 or 3 electrons their valency is also 1, 2 or 3 respectively. If an element has 4 valence electrons, it shares all 4 electrons, so the valency is 4. If the number of valence electrons are 5, 6 or 7 electrons, then such elements accept 3, 2 or 1 electrons respectively. Thus their valency is 3, 2 or 1. When the valence electrons are 2 (for only one shell) or 8 then it is a stable electronic configuration. Thus, the valency is zero.