Element Neptunium
A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus.
Neptunium is a chemical element with the symbol Np and atomic number 93.
Neptunium is a hard, silvery, ductile, radioactive actinide metal. In the periodic table, it is located to the right of the actinide uranium, to the left of the actinide plutonium and below the lanthanide promethium
Names and Identifiers
| Chemical Formula: | Np |
| CAS: | 7439-99-8 |
| Molecular Weight: | 123.10900 g/mol |
| EC Number : | n/a |
| MDL Number: | n/a |
| Color: | silvery metallic |
| Other Names: | Nettunio |
| PubChem CID: | 23933 |
| IUPAC Name: | Neptunium |
| Inchl: | InChI=1S/Np |
| InChI Key: | LFNLGNPSGWYGGD-UHFFFAOYSA-N |
| Canonical SMILES: | [Np] |
| ICSC Number: | n/a |
Physical & Chemical Properties
| Phase: | Solid |
| Density: | 19.38 g/cm³ |
| Boiling Point: | 4447 K (4174 °C, 7545 °F) |
| Melting Point: | 912±3 K (639±3 °C, 1182±5 °F) |
| Molecular Formula: | Np |
| Flash Point: | n/a |
| Exact Mass: | 123.03200 |
24 neptunium radioisotopes have been characterized with the most stable being 237Np with a half-life of 2.14 million years, 236Np with a half-life of 154,000 years, and 235Np with a half-life of 396.1 days
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 234Np | 234.04289 | 4.4 d | EC to 234U | 0 | |
| 235Np | 235.04406 | 1.058 y | EC to 235U; α to 231Pa | 5/2 | |
| 236Np | 236.04657 | 155000 y | EC to 236U; α to 232Pa; β– to 236Pu | 6 | |
| 237Np | 237.0481678 (23) | 2.14 x 106 y | α to 233Pa; SF | 5/2 | 3.14 |
| 238Np | 238.05094 | 2.117 d | β– to 238Pu | 2 | |
| 239Np | 239.05293 | 2.355 d | β– to 239Pu | 5/2 |