Periodic Table/Neptunium
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93Np237 Da

Neptunium

Actinide·Period 7·f-block

Radioactive metallic transuranic element, belongs to the actinoids. Np-237, the most stable isotope, has a half-life of 2.2*10^6 years and is a by product of nuclear reactors. The other known isotopes have mass numbers 229 through 236, and 238 through 241. Np-236 has a half-life of 5*10^3 years. First produced by Edwin M. McMillan and P.H. Abelson in 1940.

Gallery

Neptunium 237 sphere (6 kg)

Los Alamos National Laboratory,, Public domain, via Wikimedia Commons

Bohr model of Neptunium

Physical Propertiesmass · density · phase · crystal

Atomic Mass

237Da

Density

20.2000g/cm³

Phase (STP)

Solid

Melting Point

917.1K

Boiling Point

—

Molar Heat

—

Crystal Structure

ORC

Lattice Constant

4.720Å

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

175.00pm

Covalent

171.00pm

Van der Waals

239.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Rn] 5f4 6d 7s2

Electron Shells

2, 8, 18, 32, 22, 9, 2

Electronegativity

1.30Pauling

Electron Affinity

—

1st Ionization Energy

6.3kJ/mol

Oxidation States

+3, +4, +5, +6, +7

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑↓
↑↓
↑↓
3d10
↑↓
4s2
↑↓
↑↓
↑↓
4p6
↑↓
↑↓
↑↓
↑↓
↑↓
4d10
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
4f14
↑↓
5s2
↑↓
↑↓
↑↓
5p6
↑↓
↑↓
↑↓
↑↓
↑↓
5d10
↑↓
6s2
↑↓
↑↓
↑↓
6p6
↑
↑
↑
↑
5f4
↑
6d1
↑↓
7s2

Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f4 6d1 7s2Short: [Rn] 5f4 6d 7s2

Ionization Energies (93 known)

1st6.3 kJ/mol2nd11.5 kJ/mol3rd19.7 kJ/mol4th33.8 kJ/mol5th48.0 kJ/mol6th65.0 kJ/mol7th92.0 kJ/mol8th107.0 kJ/mol9th121.0 kJ/mol10th136.0 kJ/mol11th151.0 kJ/mol12th179.0 kJ/mol13th196.0 kJ/mol14th233.0 kJ/mol15th252.0 kJ/mol16th355.0 kJ/mol17th382.0 kJ/mol18th408.0 kJ/mol19th438.0 kJ/mol20th466.0 kJ/mol21th495.0 kJ/mol22th535.0 kJ/mol23th565.0 kJ/mol24th596.0 kJ/mol25th626.0 kJ/mol26th770.0 kJ/mol27th810.0 kJ/mol28th850.0 kJ/mol29th880.0 kJ/mol30th980.0 kJ/mol31th1020.0 kJ/mol32th1130.0 kJ/mol33th1170.0 kJ/mol34th1280.0 kJ/mol35th1360.0 kJ/mol36th1430.0 kJ/mol37th1510.0 kJ/mol38th1590.0 kJ/mol39th1670.0 kJ/mol40th1740.0 kJ/mol41th1820.0 kJ/mol42th1910.0 kJ/mol43th1990.0 kJ/mol44th2070.0 kJ/mol45th2140.0 kJ/mol46th2230.0 kJ/mol47th2310.0 kJ/mol48th2675.0 kJ/mol49th2745.0 kJ/mol50th2817.0 kJ/mol51th2894.0 kJ/mol52th2969.0 kJ/mol53th3041.0 kJ/mol54th3181.0 kJ/mol55th3255.0 kJ/mol56th3338.0 kJ/mol57th3413.0 kJ/mol58th3718.0 kJ/mol59th3792.0 kJ/mol60th3872.0 kJ/mol61th3947.0 kJ/mol62th4353.0 kJ/mol63th4441.0 kJ/mol64th4658.0 kJ/mol65th4744.0 kJ/mol66th7610.0 kJ/mol67th7770.0 kJ/mol68th7950.0 kJ/mol69th8130.0 kJ/mol70th8310.0 kJ/mol71th8480.0 kJ/mol72th8890.0 kJ/mol73th9070.0 kJ/mol74th9270.0 kJ/mol75th9450.0 kJ/mol76th9970.0 kJ/mol77th10130.0 kJ/mol78th10300.0 kJ/mol79th10470.0 kJ/mol80th11730.0 kJ/mol81th11930.0 kJ/mol82th12320.0 kJ/mol83th12500.0 kJ/mol84th25870.0 kJ/mol85th26300.0 kJ/mol86th26770.0 kJ/mol87th27210.0 kJ/mol88th31910.0 kJ/mol89th32500.0 kJ/mol90th33300.0 kJ/mol91th33722.2 kJ/mol92th132911.0 kJ/mol93th135202.0 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

438
464
Np emission
380nm750nm
438.0 nm(100%)464.0 nm(50%)

Abundanceby mass

Biological Role

Toxic

Synthetic, radioactive. No biological role. Trace amounts from nuclear reactors.

Discovery

Discovered By

E.M. McMillan, P.H. Abelson

Named By

—

Year

1940

Nuclear Data

Known Isotopes

27

Stable Isotopes

0

Stable Mass Numbers

None

Isotopes of Np27 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
219Np93126219.031602570 μsα (1%)9/2-—
220Np93127220.03271629.0 nsα (1%)1-—
221Np93128221.032110Unknownα9/2-—
243Np93150243.0642041.85 minβ⁻ (1%)5/2+—
244Np93151244.0678912.29 minβ⁻ (1%)7-—
245Np93152245.070693Unknownβ⁻5/2+—

Click any isotope for its full page with decay chain:

219Np220Np221Np222Np223Np224Np225Np226Np227Np228Np229Np230Np231Np232Np233Np234Np235Np236Np237Np238Np239Np240Np241Np242Np243Np244Np245Np
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