93[237]NpNeptunium
Neptunium (Np) — element 93actinide · period 7
Neptunium is a chemical element with the symbol Np and atomic number 93. It is an actinide in period 7 of the periodic table (the f-block), with a standard atomic mass of [237] u. At room temperature (25 °C) neptunium is a solid.
💡 Known for: The first transuranium element, made in 1940 and named after the planet Neptune.
# Neptunium properties
| Symbol | Np |
|---|---|
| Atomic number | 93 |
| Atomic mass | [237] u |
| Category | actinide |
| Group | — (f-block, no group number) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f⁴ 6d¹ 7s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁴ 6s² 6p⁶ 6d¹ 7s² |
| Electrons per shell | 2, 8, 18, 32, 22, 9, 2 |
| Protons / electrons | 93 / 93 |
| State at 25 °C | solid |
| Melting point | 917 K (643.9 °C, 1190.9 °F) |
| Boiling point | 4273 K (3999.8 °C, 7231.7 °F) |
| Density | 20.45 g/cm³ |
| Electronegativity (Pauling) | 1.36 |
| First ionization energy | 6.266 eV |
| Atomic radius | 175 pm |
| Discovered | 1940 |
# Electron configuration of neptunium
The electron configuration of neptunium is [Rn] 5f⁴ 6d¹ 7s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁴ 6s² 6p⁶ 6d¹ 7s². Its 93 electrons fill 7 shells as 2, 8, 18, 32, 22, 9, 2, so the outermost shell holds 2 electrons.
# Related elements
UUraniumprevious elementPuPlutoniumnext elementAcActiniumactinideThThoriumactinidePaProtactiniumactinideAmAmericiumactinideCmCuriumactinideBkBerkeliumactinideCfCaliforniumactinideEsEinsteiniumactinide
# Neptunium FAQ
What is the atomic number of neptunium?
The atomic number of neptunium is 93: every neptunium atom has 93 protons in its nucleus. Its symbol is Np.
What is the atomic mass of neptunium?
The standard atomic mass of neptunium is [237] u (the mass number of its longest-lived isotope, since it has no stable isotopes).
What is the electron configuration of neptunium?
Neptunium's electron configuration is [Rn] 5f⁴ 6d¹ 7s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁴ 6s² 6p⁶ 6d¹ 7s²), with 2, 8, 18, 32, 22, 9, 2 electrons per shell.
Is neptunium a metal?
Yes. Neptunium is an actinide, one of the metals.
What is the melting point of neptunium?
Neptunium melts at 917 K (643.9 °C, 1190.9 °F) and boils at 4273 K (3999.8 °C, 7231.7 °F).
What is neptunium used for / known for?
The first transuranium element, made in 1940 and named after the planet Neptune.