Aluminium-25

Properties and data of the isotope ²⁵Al.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Aluminium-25 is a radioisotope of the chemical element aluminium, which has 12 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 25. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁵Al is exclusively for academic purposes.

The first observation of the isotope during irradiation of enriched magnesium-24 with 418 keV protons was reported by Churchill et al. in 1953 [1].

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

General data

Name of the isotope:Aluminium-25; Al-25Symbol:²⁵Al or 2513AlMass number A:25 (= number of nucleons)Atomic number Z:13 (= number of protons)Neutrons N:12Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):0.92307692307692 (= neutron-proton ratio)Neutron excess (N-Z):-1Isotopic mass:24.99042831(7) u (atomic weight of Aluminium-25)Nuclide mass:24.9832968 u (calculated nuclear mass without electrons)Mass excess:-8.91597 MeVMass defect:0.215276098 u (per nucleus)Nuclear binding energy:200.52839363 MeV (per nucleus)
8.02113575 MeV (average binding energy per nucleon)Separation energy:S_N = 16.93848(24) MeV (first neutron)
S_P = 2.27137(7) MeV (first proton)Half-life:7.183(12) sDecay constant λ:0.096498284917158 s^-1Specific activity α:2.421359435472 × 10⁺²¹ Bq g^-1
65442146904.665 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = 3.6447(12)Nuclear g-factor:g_l = 1.45788Mirror nucleus:Magnesium-25Year of discovery:1953

Radioactive Decay

Half-life T_½ = 7.183(12) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	²⁵Mg	100 %	4.27681(8) MeV

Parent Nuclides

Direct parent isotopes are: ²⁵Si, ²⁶P, ²⁷S.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 12) and isobaric (same nucleon number A = 25) with Aluminium-25. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 12	Isobar A = 25
4	¹⁶Be
5	¹⁷B
6	¹⁸C
7	¹⁹N	²⁵N
8	²⁰O	²⁵O
9	²¹F	²⁵F
10	²²Ne	²⁵Ne
11	²³Na	²⁵Na
12	²⁴Mg	²⁵Mg
13	²⁵Al	²⁵Al
14	²⁶Si	²⁵Si
15	²⁷P	²⁵P
16	²⁸S
17	²⁹Cl
18	³⁰Ar
19	³¹K