Final answer:
The elements N and O spell Nitrogen and Oxygen. When combined, they form chemically reactive compounds.
Step-by-step explanation:
N & O spell the elements Nitrogen and Oxygen. Nitrogen has one full lone pair and one additional electron, while Oxygen has two lone pairs. When combined, Nitrogen and Oxygen form compounds such as Nitric Acid (HNO3), which are chemically reactive due to the odd-electron nature.