Relative atomic mass: [237]

English: Neptunium
French: Neptunium
Croatian: Neptunij
German: Neptunium
Italian: Nettunio
Spanish: Neptunio

Atomic number: 93
Group numbers: 3
Period: 7
Standard state (20 oC): solid

Discovery: 1940 Edwin Mattison McMillan, Philip Hauge Abelson (US)
Neptunium was discovered by Edwin Mattison McMillan and Philip Hauge Abelson (US) in 1940. Named after the planet Neptune. It is a rare, silvery radioactive, radiotoxic metal that resists alkalis, reacts with oxygen, acid and steam. Neptunium was produced by bombarding uranium with slow neutrons.
Electronic configuration: [Rn] 5f4 6d1 7s2
Formal oxidation number: +3 +4 +5 +6
Atomic radius: 130 pm

Electronegativities: 1.3
Thermal conductivity: 6.3 W/(m K)
Electrical resistivity (20 oC): 122 microOhm cm

Melting point: 644 oC
Boiling point: 3902 oC

Heat of fusion: 9.46 kJ/mol
Heat of vaporization: 336.6 kJ/mol
Heat of atomization: 457 kJ/mol

92U <= 93Np => 94Pu

ASCII Periodic Table of the Elements
6 Jan. 2020
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