Let me give you some basic and interesting facts from Mendeleev’s periodic table about neptunium―an element that was named after the planet Neptune.
American physicist and Nobel laureate Edwin McMillan, and Philip H. Abelson, a physicist and a scientific editor, are the people who were responsible for adding one more element to Mendeleev’s Periodic table―neptunium. As mentioned before, this element has been named after the planet Neptune. It was discovered in 1940, at the Berkeley Radiation Laboratory, situated in the University of California, Berkeley. The chemical elements which possess an atomic number greater than 92 are known as ‘transuranic elements’. Neptunium, a radioactive metallic element, is known to be the first of such elements.
| Properties | |
| Symbol | Np |
| Atomic Number (No. of protons or electrons) | 93 |
| Atomic Mass | 237.0482 amu (atomic mass unit) |
| Electronic Configuration | 5f4 6d1 7s2 |
| Number of Neutrons | 144 |
| Melting Point | 913 K (Kelvin) |
| Boiling Point | 4175 K |
| Crystal Structure (Lattice Structure) | Orthorhombic |
| Density | 20.25 g/cc |
| Atomic Radius | 130 pm |
| Oxidation States | 6, 5, 4, 3 |
| Evaporation Heat | 336 kJ/mol |
| Atomic Volume | 21.1 cc/mol |
Isotopes
Isotopes are known to be among the most important parts of an element. They are simply defined as one of two or more atoms, which although have the same atomic number, have different number of neutrons. For this particular element, there are 20 isotopes known till date. The element neptunium is not stable, and it radioactively decays into other elements. This is the reason why it has an extremely short half-life, thus, making it rare and even non-existent in some parts of the Earth. One isotope of this element which is known to be the most stable is neptunium-237. It has a half-life of 2.14 million years.
Uses
As mentioned before, neptunium-237 is the most stable isotope of this element, and it is the one employed in various processes. It is used in neutron-detection equipment. It is bombarded with neutrons for the production of plutonium-238 (radioactive isotope of plutonium; half-life of 87.7 years).
Neptunium may also find applications in weaponry, but theoretically, it has the property to sustain a chain reaction of nuclear fission. Although there has been no procedure which has used this element for the manufacturing of weapons, according to the U.S. Department of Energy, it can be used for such purposes. And because of this, in some regions of the world, access to it is restricted.
Apart from this, the radioactive element is also employed for high-energy (MeV) neutrons.
Some More Facts
- Usually, reaction between two metals is rare. However, given the reactive nature of this element, it forms compounds like neptunium dialuminide (NpAL 2 ) and neptunium beryllide (NpBe 3 ).
- Earlier, this element was assumed to be man-made, in other words, artificial. However, it was later discovered that trace amounts of the element are present in the Earth’s crust. Also, although rare, it is also found in uranium ores and in those of other radioactive elements.
Neptunium is one of those elements which are considered harmful to living beings. Due to obvious reasons, the radiation emitted by the substance results in severe health conditions, both in humans as well as animals. This type of radiation does not kill but it damages the body cells, which in turn may lead to abnormal cell reproduction.