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neptunium
Neptunium information, including Technical Data, Safety Data and its high purity properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity and thermal properties are included.

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Neptunium Bohr ModelNeptunium is a Block F, Group 3, Period 7 element. The number of electrons in each of Neptunium's shells is 2, 8, 18, 32, 22, 9, 2 and its electronic configuration is [Rn] 5f4 6d1 7s2. In its elemental form neptunium 's CAS number is 7439-99-8. The neptunium atom has a radius of 130.pm and it's Van der Waals radius is 200.pm.

Neptunium was discovered by Edwin M. McMillan and P. H. Abelson in 1940.

Neptunium was named for the planet Neptune.



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Neptunium Abundance. The following table shows the abundance of neptunium and each of its naturally occurring isotopes on Earth along with the atomic mass for each isotope.
Isotope Atomic Mass % Abundance on Earth
Np-237 237.048167 -


Neptunium Safety Data. The safety data for neptunium metal, nanoparticles and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the left margin. Neptunium compounds have no biological role.

Ionization Energy. The ionization energy for neptunium (the least required energy to release a single electron from the atom in it's ground state in the gas phase) is stated in the following table:
1st Ionization Energy 604.55 kJ mol-1
2nd Ionization Energy - kJ mol-1
3rd Ionization Energy - kJ mol-1


Conductivity. As to neptunium 's electrical and thermal conductivity, the electrical conductivity measured in terms of electrical resistivity @ 20 ºC is 122 µOcm and its electronegativities (or its ability to draw electrons relative to other elements) is 1.3. The thermal conductivity of neptunium is 6.3 W m-1 K-1.

Thermal Properties of Neptunium . The melting point and boiling point for neptunium are stated below. The following chart sets forth the heat of fusion, heat of vaporization and heat of atomization.
Heat of Fusion 9.46kJ mol-1
Heat of Vaporization 336.6 kJ mol-1
Heat of Atomization 457 kJ mol-1


Recent Research & Development for Neptunium
  • Rapid determination of 237np and plutonium isotopes in urine by inductively-coupled plasma mass spectrometry and alpha spectrometry. Maxwell SL, Culligan BK, Jones VD, Nichols ST, Noyes GW, Bernard MA. Health Phys. 2011 Aug;101(2):180-6. PMID: 21709507 [PubMed - in process]

  • Genomic analysis reveals versatile organisms for quorum quenching enzymes: acyl-homoserine lactone-acylase and -lactonase. Kalia VC, Raju SC, Purohit HJ. Open Microbiol J. 2011;5:1-13. Epub 2011 Feb 8. PMID: 21660112 [PubMed]

  • Resonant x-ray scattering investigation of magnetic ordering in NpAs(1 - x)Se(x) (x = 0.05, 0.10). Rodrigues VH, Paixão JA, Costa MM, Mannix D, Bombardi A, Rebizant J, Lander GH. J Phys Condens Matter. 2011 Jan 19;23(2):026002. Epub 2010 Dec 13. PMID: 21406852 [PubMed - indexed for MEDLINE]

  • Reinvestigation of the M emission spectrum of uranium-92. Dellith J, Scheffel A, Terborg R, Wendt M. Microsc Microanal. 2011 Apr;17(2):296-301. Epub 2011 Mar 16. PMID: 21406137 [PubMed - in process]

  • Reliable determination of 237Np in environmental solid samples using 242Pu as a potential tracer. Qiao J, Hou X, Roos P, Miró M. Talanta. 2011 Apr 15;84(2):494-500. Epub 2011 Jan 26. PMID: 21376978 [PubMed]

  • Role of anions and reaction conditions in the preparation of uranium(VI), neptunium(VI), and plutonium(VI) borates. Wang S, Villa EM, Diwu J, Alekseev EV, Depmeier W, Albrecht-Schmitt TE. Inorg Chem. 2011 Mar 21;50(6):2527-33. Epub 2011 Feb 3. PMID: 21291194 [PubMed - indexed for MEDLINE]

  • High-throughput sequential injection method for simultaneous determination of plutonium and neptunium in environmental solids using macroporous anion-exchange chromatography, followed by inductively coupled plasma mass spectrometric detection. Qiao J, Hou X, Roos P, Miró M. Anal Chem. 2011 Jan 1;83(1):374-81. Epub 2010 Dec 1. PMID: 21121695 [PubMed]

  • Determination of 237Np and Pu isotopes in large soil samples by inductively coupled plasma mass spectrometry. Maxwell SL, Culligan BK, Jones VD, Nichols ST, Bernard MA, Noyes GW. Anal Chim Acta. 2010 Dec 3;682(1-2):130-6. Epub 2010 Oct 8. PMID: 21056724 [PubMed]

  • Geomicrobiological redox cycling of the transuranic element neptunium. Law GT, Geissler A, Lloyd JR, Livens FR, Boothman C, Begg JD, Denecke MA, Rothe J, Dardenne K, Burke IT, Charnock JM, Morris K. Environ Sci Technol. 2010 Dec 1;44(23):8924-9. Epub 2010 Nov 3. PMID: 21047117 [PubMed - indexed for MEDLINE]

  • Neglected neptunium. Ibers J. Nat Chem. 2010 Nov;2(11):996. PMID: 20966959 [PubMed - indexed for MEDLINE]

  • Boronic acid flux synthesis and crystal growth of uranium and neptunium boronates and borates: a low-temperature route to the first neptunium(V) borate. Wang S, Alekseev EV, Miller HM, Depmeier W, Albrecht-Schmitt TE. Inorg Chem. 2010 Nov 1;49(21):9755-7. PMID: 20919728 [PubMed - indexed for MEDLINE]

  • Cerium(IV), neptunium(IV), and plutonium(IV) 1,2-phenylenediphosphonates: correlations and differences between early transuranium elements and their proposed surrogates. Diwu J, Wang S, Liao Z, Burns PC, Albrecht-Schmitt TE. Inorg Chem. 2010 Nov 1;49(21):10074-80. PMID: 20919712 [PubMed - indexed for MEDLINE]

  • Biomimetic actinide chelators: an update on the preclinical development of the orally active hydroxypyridonate decorporation agents 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO). Abergel RJ, Durbin PW, Kullgren B, Ebbe SN, Xu J, Chang PY, Bunin DI, Blakely EA, Bjornstad KA, Rosen CJ, Shuh DK, Raymond KN. Health Phys. 2010 Sep;99(3):401-7. PMID: 20699704 [PubMed - indexed for MEDLINE]

  • Structure determination of neptunium(VI) mu3-hydroxobenzoate, [(NpO2)2(mu3-OH)2(H5C6COO)2] x 2 H2O. Charushnikova IA, Krot NN, Makarenkov VI. Inorg Chem. 2010 Sep 6;49(17):7611-3. PMID: 20698554 [PubMed]

  • Determination of neptunium in environmental samples by extraction chromatography after valence adjustment. Guérin N, Langevin MA, Nadeau K, Labrecque C, Gagné A, Larivière D. Appl Radiat Isot. 2010 Dec;68(12):2132-9. Epub 2010 Jul 1. PMID: 20630769 [PubMed - indexed for MEDLINE]

  • Reconstruction of local fallout composition and gamma-ray exposure in a village contaminated by the first USSR nuclear test in the Semipalatinsk nuclear test site in Kazakhstan. Imanaka T, Yamamoto M, Kawai K, Sakaguchi A, Hoshi M, Chaizhunusova N, Apsalikov K. Radiat Environ Biophys. 2010 Nov;49(4):673-84. Epub 2010 Jun 8. PMID: 20532543 [PubMed - indexed for MEDLINE]

  • Surface complexation of Neptunium(V) onto whole cells and cell components of Shewanella alga: modeling and experimental study. Deo RP, Songkasiri W, Rittmann BE, Reed DT. Environ Sci Technol. 2010 Jul 1;44(13):4930-5. PMID: 20521812 [PubMed - indexed for MEDLINE]

  • A DFT study of the reactivity of actinidocenes (U, Np and Pu) with pyridine and pyridine N-oxide derivatives. Castro L, Yahia A, Maron L. Dalton Trans. 2010 Aug 7;39(29):6682-92. Epub 2010 Jun 2. PMID: 20520886 [PubMed]

  • Synthesis of bimetallic uranium and neptunium complexes of a binucleating macrocycle and determination of the solid-state structure by magnetic analysis. Arnold PL, Potter NA, Magnani N, Apostolidis C, Griveau JC, Colineau E, Morgenstern A, Caciuffo R, Love JB. Inorg Chem. 2010 Jun 21;49(12):5341-3. PMID: 20503974 [PubMed - indexed for MEDLINE]

  • Further insights into intermediate- and mixed-valency in neptunium oxoanion compounds: structure and absorption spectroscopy of K2[(NpO2)3B10O16(OH)2(NO3)2]. Wang S, Alekseev EV, Depmeier W, Albrecht-Schmitt TE. Chem Commun (Camb). 2010 Jun 14;46(22):3955-7. Epub 2010 Apr 30. PMID: 20436970 [PubMed]
  •  
    Formula Atomic Number Molecular Weight Electronegativity (Pauling) Density Melting Point Boiling Point Vanderwaals radius Ionic radius Energy of first ionization
    Np 93 237 g.mol -1 1.36 20.2 g/L 637  °C 4000 °C .200 nm 130 pm 604.55 kJ.mol-1

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