World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000503241
Reproduction Date:

Title: Nitrogen-14  
Author: World Heritage Encyclopedia
Language: English
Subject: Oxygen, Stable nuclide, Meselson–Stahl experiment, Electron neutrino, N14, Isotopes of carbon, Egyptian chronology, Table of nuclides, Activation product
Publisher: World Heritage Encyclopedia


Natural nitrogen (N) consists of two stable isotopes, nitrogen-14, which makes up the vast majority of naturally occurring nitrogen, and nitrogen-15. Fourteen radioactive isotopes (radioisotopes) have also been found so far, with atomic masses ranging from 10 to 25, and one nuclear isomer, 11mN. All of these radioisotopes are short-lived, with the longest-lived one being nitrogen-13 with a half-life of 9.965 minutes. All of the others have half-lives below 7.15 seconds, with most of these being below five-eighths of a second. Most of the isotopes with atomic mass numbers below 14 decay to isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of about 2.3 microseconds.

The standard atomic weight of nitrogen is 14.0067.

Natural isotopes


Nitrogen-14 is one of two stable (non-radioactive) isotopes of the chemical element nitrogen, which makes up about 99.636% of natural nitrogen.

Nitrogen-14 is one of the very few stable nuclides with both an odd number of protons and of neutrons (seven each). Each of these contributes a nuclear spin of plus or minus spin 1/2, giving the nucleus a total magnetic spin of one.

Like all elements heavier than lithium, the original source of nitrogen-14 and nitrogen-15 in the Universe is believed to be stellar nucleosynthesis, where they are produced as part of the carbon-nitrogen-oxygen cycle.

Nitrogen-14 is the source of naturally-occurring carbon-14. Some kinds of cosmic radiation cause a nuclear reaction with nitrogen-14 in the upper atmosphere of the Earth, creating carbon-14 which decays back to nitrogen-14 with a half-life of 5,730±40 years.[1]


Nitrogen-15 is a rare stable isotope of nitrogen. This isotope is often used in agricultural and medical research, for example in the Meselson–Stahl experiment to establish the nature of DNA replication.[2] An extension of this research resulted in development of DNA-based stable-isotope probing, which allows examination of links between metabolic function and taxonomic identity of microorganisms in the environment, without the need for culture isolation.[3][4] Nitrogen-15 is extensively used to trace mineral nitrogen compounds (particularly fertilizers) in the environment and when combined with the use of other isotopic labels, is also a very important tracer for describing the fate of nitrogenous organic pollutants.[5][6]

Nitrogen-15 is frequently used in nuclear magnetic resonance spectroscopy (NMR), because unlike the more abundant nitrogen-14, that has an integer nuclear spin and thus a quadrupole moment, N-15 has a fractional nuclear spin of one-half, which offers advantages for NMR like narrower line width. Proteins can be isotopically labelled by cultivating them in a medium containing nitrogen-15 as the only source of nitrogen. In addition, nitrogen-15 is used to label proteins in quantitative proteomics (e.g. SILAC).

Also, the ratio of 15N/14N in an organism can give clues about its diet, as movement up the food chain tends to concentrate the 15N isotope, by 3-4‰ with each step of the food chain - see Isotopic signatures - Nitrogen Isotopes.

Two sources of nitrogen-15 are the positron emission of oxygen-15[7] and the beta decay of carbon-15.


Z(p) N(n)  
isotopic mass (u)
half-life decay mode(s)[8] daughter
isotope(s)[n 1]
(mole fraction)
range of natural
(mole fraction)
excitation energy
10N 7 3 10.04165(43) 200(140)×10−24 s
[2.3(16) MeV]
p 9C (2−)
11N 7 4 11.02609(5) 590(210)×10−24 s
[1.58(+75−52) MeV]
p 10C 1/2+
11mN 740(60) keV 6.90(80)×10−22 s 1/2−
12N 7 5 12.0186132(11) 11.000(16) ms β+ (96.5%) 12C 1+
β+, α (3.5%) 8Be[n 2]
13N[n 3] 7 6 13.00573861(29) 9.965(4) min β+ 13C 1/2−
14N 7 7 14.0030740048(6) Stable 1+ 0.99636(20) 0.99579–0.99654
15N 7 8 15.0001088982(7) Stable 1/2− 0.00364(20) 0.00346–0.00421
16N 7 9 16.0061017(28) 7.13(2) s β (99.99%) 16O 2−
β, α (.001%) 12C
17N 7 10 17.008450(16) 4.173(4) s β, n (95.0%) 16O 1/2−
β (4.99%) 17O
β, α (.0025%) 13C
18N 7 11 18.014079(20) 622(9) ms β (76.9%) 18O 1−
β, α (12.2%) 14C
β, n (10.9%) 17O
19N 7 12 19.017029(18) 271(8) ms β, n (54.6%) 18O (1/2−)
β (45.4%) 19O
20N 7 13 20.02337(6) 130(7) ms β, n (56.99%) 19O
β (43.00%) 20O
21N 7 14 21.02711(10) 87(6) ms β, n (80.0%) 20O 1/2−#
β (20.0%) 21O
22N 7 15 22.03439(21) 13.9(14) ms β (65.0%) 22O
β, n (35.0%) 21O
23N 7 16 23.04122(32)# 14.5(24) ms
[14.1(+12−15) ms]
β 23O 1/2−#
24N 7 17 24.05104(43)# <52 ns n 23N
25N 7 18 25.06066(54)# <260 ns 1/2−#


  • The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
  • 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.
  • Nuclide masses are given by IUPAP Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO).
  • Isotope abundances are given by IUPAC Commission on Isotopic Abundances and Atomic Weights.


  • Isotope masses from:
  • Isotopic compositions and standard atomic masses from:
  • Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.

Isotopes of carbon Isotopes of nitrogen Isotopes of oxygen
Table of nuclides
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Hawaii eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.