Neptunium
Symbol
Np
Atomic Number
93
Atomic Weight
237.048
Element Classification
Discovered By
E.M. McMillan, P.H. Abelson
Discovery Date
1940 (United States)
Name Origin
Named for the planet Neptune.
Density (g/cc)
20.25
Melting Point (K)
913
Boiling Point (K)
4175
Appearance
Silvery metal
Atomic Radius (pm)
130
Atomic Volume (cc/mol)
21.1
Covalent Radius (pm)
n/a
Ionic Radius
95 (+4e) 110 (+3e)
Specific Heat
n/a
Fusion Heat (kJ/mol)
(9.6)
Evaporation Heat (kJ/mol)
336
Thermal Conductivity (@25°C W/m K)
(6.3)
Debye Temperature (K)
n/a
Pauling Negativity Number
1.36
First Ionizing Energy (kJ/mol)
n/a
Oxidation States
6, 5, 4, 3
Electronic Configuration
[Rn] 5f4 6d1 7s2
Lattice Structure
Orthorhombic(ORC)
Lattice Constant
4.720
Lattice C/A Ratio
n/a
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