Atomic number 93
Neptunium
Actinide
No photo: here’s why
Neptunium is synthetic, forged in nuclear reactors and handled only behind heavy shielding. It exists in real amounts, but never anywhere you would encounter it.
Quick facts
- Atomic mass
- 237.00
- Group
- –
- Period
- 7
- State (STP)
- solid
- Electronegativity
- 1.36
- Common ox. states
- +3, +4, +5, +6, +7
Properties
[Rn] 5f⁴ 6d¹ 7s²
- Ionization energy
- 604.5 kJ/mol
- Electron affinity
- –
- Melting point
- 917.00 K (643.9 °C)
- Boiling point
- 4273.00 K (3999.8 °C)
How dangerous is it?
A man made metal that is strongly radioactive, made only in tiny amounts and never found loose in everyday life.
- RadioactiveImmediate and cumulative
It steadily releases alpha radiation that barely reaches you from outside but harms cells if it gets into the body. (mainly a hazard once inhaled or swallowed, not across a room)
Made and studied only in shielded gloveboxes at licensed labs, handled with remote tools.
- ToxicBuilds up over time
Like the other heavy actinides it acts as a chemical poison if it works its way inside.
Kept sealed away so it cannot be eaten, breathed, or absorbed.
How it bonds· family overview
Neptunium (Np) is an actinide. Like the lanthanides it tends toward a +3 oxidation state, but the early actinides (Th–Am) routinely access +4, +5, +6, even +7 because the 5f electrons are easier to ionize. Most actinides are radioactive; their "bonding" in school is read off the periodic table, not measured in lab.
