Question

significance of valence electron

Answer 1

Valence electrons are the electrons which are present in the outermost shell of an atom.
When two atoms approach each other and react with each other, it is their outer shells that come into contact first, and it is therefore the electrons in their outer shells that are normally involved in any chemical reaction.  So it is the number of electrons in an atom’s outer shell that determines, to a large extent, how that element will react chemically.

The periodic table is arranged such that elements in the same column have the same number of electrons in their outer shell.

Answer 2

Valence electrons are the electrons which are present in the outermost shell of an atom. It is the number of electrons in an atom’s outer shell that determines, to a large extent, how that element will react chemically. Thus, valence electrons play a very significant role.