Aluminium-22

Properties and data of the isotope ²²Al.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Aluminium-22 is a radioisotope of the chemical element aluminium, which has 9 neutrons in its atomic nucleus in addition to the element-specific 13 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 22. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²²Al is exclusively for academic purposes.

The first observation of the proton-rich isotope was reported in 1982 [1]: The synthesis of the nuclide ²²Al was achieved by irradiating a magnesium-24-containing template with a 110 MeV helium-3 beam:

²⁴Mg(³He,p4n)²²Al .

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

General data

Name of the isotope:Aluminium-22; Al-22Symbol:²²Al or 2213AlMass number A:22 (= number of nucleons)Atomic number Z:13 (= number of protons)Neutrons N:9Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):0.69230769230769 (= neutron-proton ratio)Neutron excess (N-Z):-4Isotopic mass:22.019540(430) u (atomic weight of Aluminium-22)Nuclide mass:22.0124085 u (calculated nuclear mass without electrons)Mass excess:18.20139 MeVMass defect:0.16016966 u (per nucleus)Nuclear binding energy:149.19707727 MeV (per nucleus)
6.78168533 MeV (average binding energy per nucleon)Separation energy:S_N = 16.960(721) MeV (first neutron)Half-life:91.1(5) msDecay constant λ:7.6086408403946 s^-1Specific activity α:2.082741222432 × 10⁺²³ Bq g^-1
5629030330899.7 Ci g^-1Spin and parity:
(nuclear angular momentum)(4)+Mirror nucleus:Fluorine-22Year of discovery:1982

Radioactive Decay

Half-life T_½ = 91.1(5) ms respectively 9.11 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
β⁺	²²Mg	43.862 %	18.601(401) MeV
β⁺, p	²¹Na	55 %
β⁺, 2p	²⁰Ne	1.1 %
β⁺, α	¹⁸Ne	0.038 %

Parent Nuclides

Direct parent isotope is: ²²Si.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 9) and isobaric (same nucleon number A = 22) with Aluminium-22. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 9	Isobar A = 22
3	¹²Li
4	¹³Be
5	¹⁴B
6	¹⁵C	²²C
7	¹⁶N	²²N
8	¹⁷O	²²O
9	¹⁸F	²²F
10	¹⁹Ne	²²Ne
11	²⁰Na	²²Na
12	²¹Mg	²²Mg
13	²²Al	²²Al
14	²³Si	²²Si
15	²⁴P

External data and identifiers

Adopted Levels, Gammas:NuDat 22Al

Literature and References

[1] - M. D. Cable, J. Honkanen, R. F. Parry et al.:
Beta-delayed proton decay of an odd-odd T_z=−2 isotope, ²²Al.
In: Physical Review C, 26, 1778(R), (1982), DOI 10.1103/PhysRevC.26.1778.

[2] - M. Z. Sun et al.:
Ground-state mass of ²²Al and test of state-of-the-art ab initio calculations.
In: Chinese Physics C, 48, 034002, (2024), DOI 10.1088/1674-1137/ad1a0a.