Aluminium-27

Properties and data of the isotope ²⁷Al.

Contents

General Data

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Aluminium-27 is the only stable isotope of the chemical element aluminium, which has 14 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 27. The discovery of ²⁷Al using a so-called Cavendish mass spectrometer was reported by F. W. Aston in 1922 [1].

General data

Name of the isotope:Aluminium-27; Al-27Symbol:²⁷Al or 2713AlMass number A:27 (= number of nucleons)Atomic number Z:13 (= number of protons)Neutrons N:14Isotopic mass:26.9815385(7) u (atomic weight of Aluminium-27)Nuclide mass:26.974407 u (calculated nuclear mass without electrons)Mass excess:-17.19678 MeVMass defect:0.24149574 u (per nucleus)Nuclear binding energy:224.95183284 MeV (per nucleus)
8.33154936 MeV (average binding energy per nucleon)Separation energy:S_N = 13.05804(8) MeV (first neutron)
S_P = 8.27129(6) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = +3.64070(2)Charge radius:3.0610(31) femtometer fmMirror nucleus:Silicon-27Year of discovery:1922

Parent Nuclides

Direct parent isotopes are: ²⁷Mg, ²⁷Si, ²⁸P.

Occurrence

Comparison of the natural Aluminium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Aluminium Isotopic mixture	26.9815384 u	100 %
Isotope ²⁶Al	25.98689188(7) u	[trace]	7.17(24) × 10⁵ a	5+
Isotope ²⁷Al	26.9815385(7) u	100 %	stable	5/2+

NMR data

Nuclear magnetic properties of the NMR active Nuclide ²⁷Al

Isotope:²⁷Al-NMRQuantity:100 %Spin:5/2+Nuclearmagnetic moment
μ/μ_N:+3.64070(2)Gyromagnetic ratio γ:6.976 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 1.45628Quadrupole moment Q:+ 0.1466(10) barn (100 fm²)Resonance frequency:v₀ = 11.1031 at 1 TFrequency ratio:Ξ(²⁷Al) = 26.056859 %Relative Sensitivity:0.20689 (H₀ = const.)
3.0424 (v₀ = const.)
[related to ¹H = 1.000]Reference compound:
(conditions)Solution of 1.1 m aluminium nitrate Al(NO₃)₃ in deuterium oxide D₂O.

The nuclide aluminum-27 has a very sensitive quadrupolar atomic nucleus, which is suitable for ²⁷Al NMR spectroscopy and shows broad lines in the NMR spectrum over a wide chemical shift range. The signal width increases with the asymmetry of the chemical environment in the molecule.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 14) and isobaric (same nucleon number A = 27) with Aluminium-27. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 14	Isobar A = 27
5	¹⁹B
6	²⁰C
7	²¹N
8	²²O	²⁷O
9	²³F	²⁷F
10	²⁴Ne	²⁷Ne
11	²⁵Na	²⁷Na
12	²⁶Mg	²⁷Mg
13	²⁷Al	²⁷Al
14	²⁸Si	²⁷Si
15	²⁹P	²⁷P
16	³⁰S	²⁷S
17	³¹Cl
18	³²Ar
19	³³K
20	³⁴Ca

External data and identifiers

Adopted Levels, Gammas:NuDat 27Al

Literature and References

[1] - F. W. Aston:
The Isotopes of Selenium and some other Elements.
In: Nature, 110, 664, (1922), DOI 10.1038/110664a0.

[2] - Mohamed Haouas, Francis Taulelle, Charlotte Martineau:
Recent advances in application of ²⁷Al NMR spectroscopy to materials science.
In: Progress in Nuclear Magnetic Resonance Spectroscopy, 94-95, (2016), DOI 10.1016/j.pnmrs.2016.01.003.