Np - Neptunium

There is no neptunium in our lab. Neptunium was produced by E. M. McMillan (who shared the 1951 Nobel Prize for Chemistry with Glenn Seaborg for the discovery of this and other transuranic elements) and P. Abelson in 1940 at Berkeley, and found naturally occuring in trace amounts in uranium minerals by Seaborg and Perlman in 1948.

Atomic number - 93 Density g/mL 20 .4

Atomic weight u 237 .0482 Melting point K 910

Bonding radius A - Boiling point K -

Atomic radius A - Heat of vaporization kJ/mol -

Ionization Potential V 6 .19 Heat of fusion kJ/mol 5 .19

Electronegativity - 1 .36 Specific heat J/gK 0 .12

The oxide is amphoteric.
Crystal are orthorhombic.

Electron config. : [Rn] 5f⁴ 6d¹ 7s²

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac** Rf Db Sg Bh Hs Mt 110 111 112 113

Lanthanides* Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Actinides ** Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Isotopes of Np: Click mass number for decay process, product for element page.

226
35 msec
a,8.200 MeV
Pa-222
226.03512 227
0.51 sec
a,7.816 MeV
Pa-223
227.03495 228
1.07 min
EC/ECF,4.480
U-228/?
228.03617 229
3.85 min
a/EC,7.010
Pa-225/U-229
229.03624 230
4.6 min
a/EC,3.610
Pa-226/U-230
230.03779 231
48.8 min
a/EC,1.840
Pa-227/U-231
231.03822 232
14.7 min
EC,2.700 MeV
U-232
232.04004

233
36.2 min
a/EC,1.230
Pa-229/U-233
233.04095 234
4.4 da
EC,1.810 MeV
U-234
234.04288 235
396.1 da
a/EC,4.679
Pa-231/U-235
235.04405 236
154E+3 yr
a/B-/EC,4.572
Pa-232/Pu-236/U-236
236.04657 237
2.144E+6 yr
a/SF,4.959
Pa-233/?
237.04816 238
2.117 da
B-,1.292 MeV
Pu-238
238.05093 239
2.3565 da
B-,1.265 MeV
Pu-239
239.05293

240
61.9 min
B-,2.200 MeV
Pu-240
240.05616 241
13.9 min
B-,1.310 MeV
Pu-241
241.05825 242
2.2 min
B-,2.700 MeV
Pu-242
242.06163 243
1.85 min
B-,2.170 MeV
Pu-243
243.06432 MASS abund.
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass

Updated by clh on 2/6/98. This is not a publication of Phoenix College.

Atomic number	-	93		Density	g/mL	20	.4
Atomic weight	u	237	.0482	Melting point	K	910
Bonding radius	A	-		Boiling point	K	-
Atomic radius	A	-		Heat of vaporization	kJ/mol	-
Ionization Potential	V	6	.19	Heat of fusion	kJ/mol	5	.19
Electronegativity	-	1	.36	Specific heat	J/gK	0	.12
The oxide is amphoteric.				Crystal are orthorhombic.
Electron config. : [Rn] 5f⁴ 6d¹ 7s²
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226 35 msec a,8.200 MeV Pa-222 226.03512	227 0.51 sec a,7.816 MeV Pa-223 227.03495	228 1.07 min EC/ECF,4.480 U-228/? 228.03617	229 3.85 min a/EC,7.010 Pa-225/U-229 229.03624	230 4.6 min a/EC,3.610 Pa-226/U-230 230.03779	231 48.8 min a/EC,1.840 Pa-227/U-231 231.03822	232 14.7 min EC,2.700 MeV U-232 232.04004
233 36.2 min a/EC,1.230 Pa-229/U-233 233.04095	234 4.4 da EC,1.810 MeV U-234 234.04288	235 396.1 da a/EC,4.679 Pa-231/U-235 235.04405	236 154E+3 yr a/B-/EC,4.572 Pa-232/Pu-236/U-236 236.04657	237 2.144E+6 yr a/SF,4.959 Pa-233/? 237.04816	238 2.117 da B-,1.292 MeV Pu-238 238.05093	239 2.3565 da B-,1.265 MeV Pu-239 239.05293
240 61.9 min B-,2.200 MeV Pu-240 240.05616	241 13.9 min B-,1.310 MeV Pu-241 241.05825	242 2.2 min B-,2.700 MeV Pu-242 242.06163	243 1.85 min B-,2.170 MeV Pu-243 243.06432	MASS abund. Halflife Particle, Energy Decay Product(s) Isotopic Mass