Oxygen atomic # 8.
Atomic # 8. Atomic mass 15.9994.
6 valance electrons how the element reacts and it reacts highly. 2 rings means how many energy levels. It is a gas so it is a non metal, so it is brittle non conductive.
group 16 means that those in the group are most alike, period 2 means that there are 2 energy rings.