For an atom to become chemically stable, ....?

Question

A. the valence shell should contain at least three electrons.

B. all eight valence electron orbits should be filled or completely taken away.

C. five electron orbits should be filled.

D. the number of protons should equal the number of neutrons

Answer 1

The answer is B. The 8 valence electron orbits should all be filled. An example is of this is neon. Note helium which only has 2 valence electron orbits, both filled, is chemically stable too

Answer 2

B.

Octet Rule - an atom with 8 valence electrons (or 2 in the case of He), is chemically inert. It doesn't need any more electrons nor give up 'excess' electrons in order to be stable.