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Element 93 - Neptunium (Np) sound

After Neptune, the planet beyond Uranus; discovered 1940. Detected first in invisible, unweighable amounts, neptunium was the first "synthetic" element made from uranium. Traces of it turn up in uranium ores, produced by stray neutrons from uranium's decay.

Properties

Atomic Number: 93
Atomic Weight: 237.0482
Electron Configuration (at ground state): 1s22s22p63s23p63d104s24p64d105s25p64f145d105f46s26p66d17s2
Oxidation States (Bold most stable): +6, +5, +4, +3
Boiling Point (K): 4175
Melting Point (K): 912
Density (at 300K -- g/cm3): 20.2
Atomic Volume (at 300K -- cm3/mol) 21.1
Mass Number (Bold naturally occurring) -- Half-Life -- Disintigration Type: 236 -- 1.1 x 105 years -- orbital electron capture, beta particle (electron) emission
237 -- 2.14 x 106 years -- alpha particle emission
239 -- 2.346 days -- beta particle (electron) emission
Atomic Radius (Å): 1.30
First Ionization Potential (V): 5.88
Electronegativity (Pauling's): 1.36
Electrical Conductivity (at 293K for polycrystalline material -- 106 (ohms)-1 cm-1): 0.8
Thermal Conductivity (at 300K -- W m-1 K-1): 6.3
Crystal Structure: Orthorhombic
Acid-Base Properties: Amphoteric