The electrons in an atom's outermost shell are referred to as the

The term "valence electrons" refers to the electrons that make up an atom's outermost shell. Valence electrons participate in the bond formation with other elements. Generally, they are of the same number in which group they are placed in the periodic table.

Valency is different than valence electrons as valency refers to the number of electrons that are required to fulfill the octet of that element whereas, valence electrons are the number of electrons present in the outermost shell of that element.