93Np[237]
Neptunium (Np)
Element 93 · Actinide
Neptunium (Np) is a chemical element with atomic number 93. It is classified as an actinide in period 7 of the periodic table (the f-block). Its most stable known isotope has mass number 237 and its ground-state electron configuration is [Rn] 5f⁴ 6d¹ 7s².
Neptunium facts
| Atomic number (Z) | 93 |
|---|---|
| Symbol | Np |
| Mass number of most stable isotope | [237] |
| Category | Actinide |
| Group | — (f-block) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f⁴ 6d¹ 7s² |
| Electronegativity (Pauling) | 1.36 |
| State at 20 °C | Solid |
| Protons / electrons | 93 / 93 |
| Neutrons (most common isotope, approx.) | 144 |
| Molar mass | 237 g/mol |