Template:Infobox neptunium

Neptunium,  ₉₃Np

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General properties
Pronunciation	Template:Infobox element/pronunciation
Appearance	silvery metallic
Standard atomic weight (Ar, standard)	Template:Infobox element/standard atomic weight
Mass number	Template:Infobox element/symbol-to-most-stable-isotope (most stable isotope)
Neptunium in the periodic table
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Atomic number (Z)	93
Group	Template:Infobox element/group
Period	period 7
Block	f-block
Element category	Template:Infobox element/category format
Electron configuration	[Rn] 5f4 6d1 7s2
Electrons per shell	2, 8, 18, 32, 22, 9, 2
Physical properties
Phase at STP	solid
Melting point	912±3 K ​(639±3 °C, ​1182±5 °F)
Boiling point	4447 K ​(4174 °C, ​7545 °F) (extrapolated)
Density (near r.t.)	alpha: 20.45 g/cm3 accepted standard value: 19.38 g/cm3
Heat of fusion	5.19 kJ/mol
[[Enthalpy of vaporization|Heat of Template:Engvar]]	336 kJ/mol
Molar heat capacity	29.46 J/(mol·K)
[[Vapor pressure|Template:Engvar pressure]] Template:Infobox element/vapor pressure table
Atomic properties
Oxidation states	Template:Infobox element/symbol-to-oxidation-state
Electronegativity	Pauling scale: 1.36
[[Ionization energy|Template:Engvar energies]]	1st: 604.5 kJ/mol
Atomic radius	empirical: 155 pm
Covalent radius	190±1 pm
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Other properties
Crystal structure	​Template:Infobox element/crystal structure Template:Infobox element/crystal structure
Thermal conductivity	6.3 W/(m·K)
Electrical resistivity	1.220 µΩ·m (at 22 °C)
Magnetic ordering	paramagnetic
CAS Number	7439-99-8
History
Naming	after planet Neptune, itself named after Roman god of the sea Neptune
Discovery	Edwin McMillan and Philip H. Abelson (1940)
Main isotopes of neptunium
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