11. This particular isotope of neptunium has a mass of 236.04657 u. 12. Neptunium is found in at least three allotropes.13. One neptunium -based Pd 5 Al 2. 14. It decays by emitting alpha particles and gamma radiation to become neptunium -237. 15. The actual element was discovered several years later, and assigned the name neptunium . 16. Neptunium is the only element that can stabilize the ? phase at higher temperatures.17. Many of the resulting compounds also have an equivalent compound that substitutes uranium for neptunium . 18. These are actinides other than uranium and plutonium and include neptunium , americium and curium. 19. Similarly, compare Uranus with Uranium, Neptune with Neptunium , and Pluto with Plutonium. 20. Similar species exist for neptunium and plutonium.
