Use
Neptunium is the first of the subseries of the actinide series known as the transuranic elements—those heavy, synthetic (man-made) radioactive elements that have an atomic numbergreater than uranium in the actinide series of the periodic table. An interesting fact is thatneptunium was artificially synthesized before small traces of it were discovered in nature. Moreis produced by scientists every year than exists in nature.Neptunium has an affinity for combining with nonmetals (as do all transuranic elements)such as oxygen, the halogens, sulfur, and carbon.