Question

Explain the relation between valency and number of unpaired electrons

Answer 1

First let's start by treating the set of valence and unpaired electrons.

All unpaired electrons are valence electrons, but all valence electrons need not be unpaired. Got that? Good, now to the next of all things.

Unpaired electrons are electrons in an orbital which are are alone, while valence electrons are just electrons that are in the outermost shell of an atom.

For example, an atom has the electronic configuration
. Now here, the electron in the
orbital is both the valence and the unpaired electron, but what if we added another electron to the atom (just assume we can do that). Then the configuration would change in the last orbital such that it will become
. Now the electron is only valence electrons, but not unpaired. This can be extended in many other ways, but this is the basic principle.