Template:Infobox neptunium

Neptunium,  ₉₃Np

General properties
Name, symbol	neptunium, Np
Appearance	silvery metallic
Pronunciation	UK /nɛpˈtjuːniəm/, US /nɛpˈtuːniəm/ nep-TEW-nee-əm, nep-TOO-nee-əm
Neptunium in the periodic table
Pm ↑ Np ↓ (Uqp) uranium ← neptunium → plutonium
Atomic number (Z)	93
Group, block	group n/a, f-block
Period	period 7
Element category	actinide
Standard atomic weight (Ar)	(237)
Electron configuration	[Rn] 5f4 6d1 7s2
per shell	2, 8, 18, 32, 22, 9, 2
Physical properties
Phase	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
Heat of vaporization	336 kJ/mol
Molar heat capacity	29.46 J/(mol·K)
vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2194 2437
Atomic properties
Oxidation states	7, 6, 5, 4, 3, 2 ​(an amphoteric oxide)
Electronegativity	Pauling scale: 1.36
Ionization energies	1st: 604.5 kJ/mol
Atomic radius	empirical: 155 pm
Covalent radius	190±1 pm
Miscellanea
Crystal structure	​orthorhombic
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)
Most stable isotopes of neptunium
iso NA half-life DM DE (MeV) DP 235Np syn 396.1 d α 5.192 231Pa ε 0.124 235U 236Np syn 1.54×105 y ε 0.940 236U β− 0.940 236Pu α 5.020 232Pa 237Np trace 2.144×106 y α 4.959 233Pa 239Np trace 2.356 d β− 0.218 239Pu

References

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