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Neptunium (Np)

From Wikipedia, the free encyclopediaNeptunium 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.

Neptunium in the periodic table

Atomic number93
Element categoryActinide

Physical properties

Phase at STPSolid
Density20.45 g/cm3
Atomic weight237 u
Melting point912 K
638.85 °C
1181.93 °F
Boiling point4447 K
4173.85 °C
7544.93 °F

Atomic properties

Electronegativity (Pauling Scale)1.36
Electron affinity45.85 kJ/mol
Oxidation states+2, +3, +4, +5, +6, +7
(an amphoteric oxide)
Ionization energies
1604.5 kJ/mol
21128 kJ/mol
31997 kJ/mol
43242 kJ/mol

Electron configuration

Elektronkonfiguration (shorthand)[Rn] 5f4 6d1 7s2
Electron configuration1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f4 6s2 6p6 6d1 7s2
Electrons per shell2, 8, 18, 32, 22, 9, 2


Discovered byEdwin McMillan
Philip Abelson
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