This MedLibrary.org supplementary page on Neptunium-239 is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
Neptunium (Np) has no stable isotopes. A standard atomic mass cannot be given.
19 neptunium radioisotopes have been characterized, with the most stable being 237Np with a half-life of 2.14 million years, 236Np with a half-life of 154,000 years, and 235Np with a half-life of 396.1 days. All of the remaining radioactive isotopes have half-lives that are less than 4.5 days, and the majority of these have half lifes that are less than 50 minutes. This element also has 4 meta states, with the most stable being 236mNp (t½ 22.5 hours).
The isotopes of neptunium range in atomic weight from 225.0339 u (225Np) to 244.068 u (244Np). The primary decay mode before the most stable isotope, 237Np, is electron capture (with a good deal of alpha emission), and the primary mode after is beta emission. The primary decay products before 237Np are element 92 (uranium) isotopes (alpha emission produces element 91, protactinium, however) and the primary products after are element 94 (plutonium) isotopes.
237Np is fissionable1. 237Np eventually decays to form bismuth, unlike most other common heavy and light nuclei which decay to make isotopes of lead.
Table
| nuclide symbol |
Z(p) | N(n) | isotopic mass (u) |
half-life | nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|
| excitation energy | |||||||
| 225Np | 93 | 132 | 225.03391(8) | 3# ms [>2 µs] | 9/2-# | ||
| 226Np | 93 | 133 | 226.03515(10)# | 35(10) ms | |||
| 227Np | 93 | 134 | 227.03496(8) | 510(60) ms | 5/2-# | ||
| 228Np | 93 | 135 | 228.03618(21)# | 61.4(14) s | |||
| 229Np | 93 | 136 | 229.03626(9) | 4.0(2) min | 5/2+# | ||
| 230Np | 93 | 137 | 230.03783(6) | 4.6(3) min | |||
| 231Np | 93 | 138 | 231.03825(5) | 48.8(2) min | (5/2)(+#) | ||
| 232Np | 93 | 139 | 232.04011(11)# | 14.7(3) min | (4+) | ||
| 233Np | 93 | 140 | 233.04074(5) | 36.2(1) min | (5/2+) | ||
| 234Np | 93 | 141 | 234.042895(9) | 4.4(1) d | (0+) | ||
| 235Np | 93 | 142 | 235.0440633(21) | 396.1(12) d | 5/2+ | ||
| 236Np | 93 | 143 | 236.04657(5) | 154(6)E+3 a | (6-) | ||
| 236mNp | 60(50) keV | 22.5(4) h | 1 | ||||
| 237Np | 93 | 144 | 237.0481734(20) | 2.144(7)E+6 a | 5/2+ | ||
| 238Np | 93 | 145 | 238.0509464(20) | 2.117(2) d | 2+ | ||
| 238mNp | 2300(200)# keV | 112(39) ns | |||||
| 239Np | 93 | 146 | 239.0529390(22) | 2.356(3) d | 5/2+ | ||
| 240Np | 93 | 147 | 240.056162(16) | 61.9(2) min | (5+) | ||
| 240mNp | 20(15) keV | 7.22(2) min | 1(+) | ||||
| 241Np | 93 | 148 | 241.05825(8) | 13.9(2) min | (5/2+) | ||
| 242Np | 93 | 149 | 242.06164(21) | 2.2(2) min | (1+) | ||
| 242mNp | 0(50)# keV | 5.5(1) min | 6+# | ||||
| 243Np | 93 | 150 | 243.06428(3)# | 1.85(15) min | (5/2-) | ||
| 244Np | 93 | 151 | 244.06785(32)# | 2.29(16) min | (7-) | ||
Notes
- Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
- Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.
References
- ^ Weiss, P. (October 26, 2002). "Little-studied metal goes critical - Neptunium Nukes?". Science News. Retrieved on 2006-09-29.
- Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
- Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
- Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
| Isotopes of uranium | Isotopes of neptunium | Isotopes of plutonium |
| Index to isotope pages · Table of nuclides | ||
Wikipedia content modification information:
- This page was last modified on 7 October 2008, at 21:17.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Neptunium-239".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.