Sodium-18

Properties and data of the isotope ¹⁸Na.

Contents

Sodium-18 is a radioisotope of the chemical element sodium, which, in addition to the element-specific 11 protons, has 7 neutrons in the atomic nucleus, resulting in the mass number 18. The very short-lived, unstable and therefore radioactive nuclide, which can only be produced artificially, has no practical significance; The study of ¹⁸Na serves exclusively academic purposes.

Sodium-18 was first identified and characterized in 2004 [1]. The unbound nucleus of the nuclide occurs as a short-lived intermediate nucleus in the 2-proton decay of magnesium-19 to neon-17 [2, 3].

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

General data

Name of the isotope:Sodium-18; Na-18Symbol:¹⁸Na or 1811NaMass number A:18 (= number of nucleons)Atomic number Z:11 (= number of protons)Neutrons N:7Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):0.63636363636364 (= neutron-proton ratio)Neutron excess (N-Z):-4Isotopic mass:18.026880(100) u (atomic weight of Sodium-18)Nuclide mass:18.0208457 u (calculated nuclear mass without electrons)Mass excess:25.03856 MeVMass defect:0.119849764 u (per nucleus)Nuclear binding energy:111.63933607 MeV (per nucleus)
6.20218534 MeV (average binding energy per nucleon)Separation energy:S_N = 17.753(111) MeV (first neutron)Half-life:1.3(4) zsDecay constant λ:5.331901388922 × 10⁺²⁰ s^-1Specific activity α:1.781199002962 × 10⁺⁴³ Bq g^-1
4.814051359359 × 10⁺³² Ci g^-1Spin and parity:
(nuclear angular momentum)(1)-Mirror nucleus:Nitrogen-18Year of discovery:2004

Radioactive Decay

Half-life T_½ = 1.3(4) zs respectively 1.3 × 10^-21 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
p	¹⁷Ne	?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 7) and isobaric (same nucleon number A = 18) with Sodium-18. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 7	Isobar A = 18
2	⁹He
3	¹⁰Li
4	¹¹Be
5	¹²B	¹⁸B
6	¹³C	¹⁸C
7	¹⁴N	¹⁸N
8	¹⁵O	¹⁸O
9	¹⁶F	¹⁸F
10	¹⁷Ne	¹⁸Ne
11	¹⁸Na	¹⁸Na
12	¹⁹Mg	¹⁸Mg
13	²⁰Al

External data and identifiers

Adopted Levels, Gammas:NuDat 18Na

Literature and References

[1] - T. Zerguerras, B. Blank, Y. Blumenfeld et al.:
Study of light proton-rich nuclei by complete kinematics measurements.
In: The European Physical Journal A, 20, (2004), DOI 10.1140/epja/i2003-10176-1.

[2] - M. Assie et al.:
Spectroscopy of the unbound nucleus ¹⁸Na.
In: International Journal of Modern Physics E, 20 (04), 971-975, (2011), DOI 10.1142/S0218301311019088.

[3] - M. Assié, F. de Oliveira Santos, T. Davinson et al.:
Spectroscopy of ¹⁸Na: Bridging the two-proton radioactivity of ¹⁹Mg.
In: Physics Letters B, 712, 3, (2012), DOI 10.1016/j.physletb.2012.04.059.