NETTUNIO

introduzione

Numero atomico: 93
Gruppo: Nessuna
Peso atomico: 237
Periodo: 7
Numero CAS: 7439-99-8

Classificazione

Metallo
Metalloide
simile a metallo
metallo alcalino
Alkali terroso
Metallo di transizione
calcogeno
alogena
Gas nobile
Lanthanoid
Actinoid
Terre rare
Platinum Metal Group
transuranici
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)

Descrizione • Usi / Funzione

Neptuniumwas the first synthetic transuranium element of the actinide series discovered; the isotope neptunium-239 was produced by McMillan and Abelson in 1940 atBerkeley, California, as the result of bombarding uranium with cyclotron-produced neutrons. The isotope neptunium-237 (half-life of 2.14 X 10^6 years) iscurrently obtained in gram quantities as a by-product from nuclear reactors in the production of plutonium. Twenty isotopes and isomers of neptuniumare now recognized. Trace quantities of the element are actually found in nature due to transmutation reactions in uranium ores produced by the neutronswhich are present. Neptunium is prepared by the reduction of Npf3 with barium or lithium vapor at about 1200°C. Neptunium metal has a silveryappearance, is chemically reactive, and exists in at least three structural modifications: a-neptunium, orthorhombic, density 20.25 g/cm^3, beta-neptunium(above 280°C), tetragonal, density (313°C) 19.36 g/cm^3; g-neptunium (above 577°C), cubic, density (600°C) 18.0 g/cm^3. Neptunium has four ionicoxidation states in solution: Np+3 (pale purple), analogous to the rare earth ion Pm+3, Np+4 (yellow green); NpO+ (green blue); and NpO++ (pale pink).These latter oxygenated species are in contrast to the rare earths which exhibit only simple ions of the (II), (III), and (IV) oxidation states in aqueoussolution. The element forms tri- and tetrahalides such as Npf3, Npf4, NpCl4, NpBr3, NpI3, and oxides of various compositions such as are found inthe uranium-oxygen system, including Np3O8 and NpO2. Fifteen isotopes of neptunium are now recognized. The O.R.N.L. has neptunium-237 available for saleto its licensees and for export. This isotope can be used as a component in neutron detection instruments. It is offered at a price of $660/g plus packingcosts. 1

Proprietà fisiche

Punto di fusione:2*  644 °C = 917.15 K = 1191.2 °F
Punto di ebollizione:2
sublimazione Point:2 
Triple Point:2 
Punto critico:2 
Densità:3  20.2 g/cm3

* - at 1 atm

configurazione elettronica

configurazione elettronica:  *[Rn] 7s2 5f5
Bloccare: f
Più alto livello di energia Occupato: 7
Elettroni di valenza: 2

numeri quantici:

n = 5
ℓ = 3
m = 1
ms = +½

bonding

elettronegatività (scala Pauling):4 1.3
Electropositivity (scala Pauling): 2.7

potenziale di ionizzazione   eV 5  kJ/mol  
potenziale di ionizzazione   eV 5  kJ/mol  
potenziale di ionizzazione   eV 5  kJ/mol  
1 6.2657    604.5

isotopi

nuclide Massa 6 Metà vita 6 spin nucleare 6 Energia di legame
225Np 225.03391(8) 3# ms [>2 μs] 9/2-# 1,715.34 MeV
226Np 226.03515(10)# 35(10) ms 1,723.41 MeV
227Np 227.03496(8) 510(60) ms 5/2-# 1,731.48 MeV
228Np 228.03618(21)# 61.4(14) s 1,739.55 MeV
229Np 229.03626(9) 4.0(2) min 5/2+# 1,747.63 MeV
230Np 230.03783(6) 4.6(3) min 1,755.70 MeV
231Np 231.03825(5) 48.8(2) min (5/2)(+#) 1,763.77 MeV
232Np 232.04011(11)# 14.7(3) min (4+) 1,762.52 MeV
233Np 233.04074(5) 36.2(1) min (5/2+) 1,770.60 MeV
234Np 234.042895(9) 4.4(1) d (0+) 1,778.67 MeV
235Np 235.0440633(21) 396.1(12) d 5/2+ 1,786.74 MeV
236Np 236.04657(5) 154(6)E+3 a (6-) 1,794.81 MeV
237Np 237.0481734(20) 2.144(7)E+6 a 5/2+ 1,802.88 MeV
238Np 238.0509464(20) 2.117(2) d 2+ 1,801.64 MeV
239Np 239.0529390(22) 2.356(3) d 5/2+ 1,809.71 MeV
240Np 240.056162(16) 61.9(2) min (5+) 1,817.78 MeV
241Np 241.05825(8) 13.9(2) min (5/2+) 1,825.85 MeV
242Np 242.06164(21) 2.2(2) min (1+) 1,824.61 MeV
243Np 243.06428(3)# 1.85(15) min (5/2-) 1,832.68 MeV
244Np 244.06785(32)# 2.29(16) min (7-) 1,840.75 MeV
I valori assegnati # non sono puramente derivati ​​da dati sperimentali, ma almeno parzialmente da tendenze sistematiche. Gira con argomenti di assegnazione deboli sono racchiusi tra parentesi. 6

Abbondanza

Composti

Informazioni sulla sicurezza


Scheda di sicurezza - ACI Alloys, Inc.

Per maggiori informazioni

Link esterno:

fonti

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:20.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(4) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(9) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).