Question

What are three other elements that have 8 valance electrons.

Answer 1

Any noble gas so anything in the farthest column to the right on the periodic table. Examples are helium, neon, argon, and krypton.  

Answer 2

8 valence electrons means that the element is stable. When we hear stable, we know the group to look at! Noble gases all have 8 valence electrons making them stable and have a full octet.

Here are some:-

Krypton
Argon
Neon