21. Plutonium, neptunium , iodine and technetium decay much more slowly and are not strong emitters. 22. He said neptunium posed a greater danger simply because there was so much more of it. 23. Neptunium has valence states from 3 to 7, which can be simultaneously observed in solutions.24. Another unique trait of neptunium dioxide is its " mysterious low-temperature ordered phase ". 25. Thus neptunium is present in nature in negligible amounts produced as intermediate decay products of other isotopes. 26. Plutonium, neptunium and americium form two basic oxides : An 2 O 3 and AnO 2. 27. Neptunium trioxide is unstable; thus, only Np 3 O 8 could be obtained so far.28. Two neptunium chlorides, NpI 3 has also been prepared by the same method as NpBr 3. 29. In nuclear reactors, neptunium dioxide can also be used as the target metal for plutonium bombardment. 30. The plutonium and neptunium arrived at Paducah in contaminated shipments of uranium from other bomb-making facilities.
