If an atom has 8 valence electrons, how many electrons does it need to gain to achieve a stable electron configuration?

The atom will neither gain or loose electrons.

Explanation:

Every element obeys octet rule which is defined as the rule in which an atom occupies eight electrons in its outermost shell.

We are given:

Number of valence electrons or number of electrons present in outermost shell = 8

The above given element is already stable because it is obeying octet rule completely.

Thus, this atom will neither gain or loose electrons to be stable.

i think its 100

i hope this !