93Np237.048172
Neptunium
Actinide
Solid at STP
Period 7Block FDiscovered 1940
[Rn]7s2 5f4 6d1
Neptunium is a chemical element with symbol Np and atomic number 93. 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.
📖 Read more on Wikipedia →Atomic Properties
| Atomic Number | 93 |
| Atomic Mass | 237.048172 u |
| Electron Configuration | [Rn]7s2 5f4 6d1 |
| Oxidation States | +6, +5, +4, +3 |
| Electronegativity | 1.36 (Pauling) |
| Atomic Radius | 221 pm |
| Ionization Energy | 6.266 eV |
| Block | F |
Physical Properties
| Appearance | silvery metallic |
| Standard State | Solid |
| Melting Point | 917 K (643.9 °C) |
| Boiling Point | 4175 K (3901.8 °C) |
| Density | 20.25 g/cm³ |
| Molar Heat | 29.46 J/(mol·K) |
| CPK Color | #0080FF |
Classification
| Category | Actinide |
| Group Block | Actinide |
| Period | 7 |
| Block | F |
Discovery
| Year Discovered | 1940 |
| Discovered By | Edwin McMillan |
| Electron Shells | 2, 8, 18, 32, 22, 9, 2 |