Nitrogen-18

Properties and data of the isotope ¹⁸N.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Nitrogen-18 is a radioisotope of the chemical element nitrogen, which has 11 neutrons in its atomic nucleus in addition to the element-specific 7 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 18. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹⁸N is exclusively for academic purposes.

The discovery of the radioactive isotope was announced in 1964. The production and detection of nitrogen-18 was achieved by irradiating water enriched with oxygen-18 (water-18O) with 19MeV neutrons according to the following transfer reaction [1]:

¹⁸O(n,p)¹⁸N.

See also: List of individual Nitrogen isotopes (and general data sources).

General data

Name of the isotope:Nitrogen-18; N-18Symbol:¹⁸N or 187NMass number A:18 (= number of nucleons)Atomic number Z:7 (= number of protons)Neutrons N:11Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.5714285714286 (= neutron-proton ratio)Neutron excess (N-Z):4Isotopic mass:18.014078(20) u (atomic weight of Nitrogen-18)Nuclide mass:18.010238 u (calculated nuclear mass without electrons)Mass excess:13.11357 MeVMass defect:0.1360113 u (per nucleus)Nuclear binding energy:126.69370988 MeV (per nucleus)
7.03853944 MeV (average binding energy per nucleon)Separation energy:S_N = 2.828(24) MeV (first neutron)
S_P = 15.208(25) MeV (first proton)Half-life:619.2(19) msDecay constant λ:1.1194237412144 s^-1Specific activity α:3.74518191752 × 10⁺²² Bq g^-1
1012211329061.6 Ci g^-1Spin and parity:
(nuclear angular momentum)1-Isobaric spin: 2Magnetic dipole moment:μ(μ_N) = 0.3273(4)Quadrupole moment Q:0.0123(12) barn (100 fm²)Nuclear g-factor:g_l = 0.3273Mirror nucleus:Sodium-18Year of discovery:1964

Radioactive Decay

Half-life T_½ = 619.2(19) ms respectively 6.192 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	¹⁸O	80.8(16) %	13.896(19) MeV
β^-, n	¹⁷O	7.0(15) %	5.851(19) MeV
β^-, α	¹⁴C	12.2(6) %
β^-, 2n	¹⁶O	?

Parent Nuclides

Direct parent isotope is: ¹⁸C.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 11) and isobaric (same nucleon number A = 18) with Nitrogen-18. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 11	Isobar A = 18
4	¹⁵Be
5	¹⁶B	¹⁸B
6	¹⁷C	¹⁸C
7	¹⁸N	¹⁸N
8	¹⁹O	¹⁸O
9	²⁰F	¹⁸F
10	²¹Ne	¹⁸Ne
11	²²Na	¹⁸Na
12	²³Mg	¹⁸Mg
13	²⁴Al
14	²⁵Si
15	²⁶P
16	²⁷S
17	²⁸Cl
18	²⁹Ar