See also: List of individual Xenon isotopes (and general data sources).
General data
Name of the isotope:Xenon-126; Xe-126Symbol:126Xe or 12654XeMass number A:126 (= number of nucleons)Atomic number Z:54 (= number of protons)Neutrons N:72Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.3333333333333 (= neutron-proton ratio)Neutron excess (N-Z):18Isotopic mass:125.90430(3) u (atomic weight of Xenon-126)Nuclide mass:125.8746786 u (calculated nuclear mass without electrons)Mass excess:-89.14398 MeVMass defect:1.14212568 u (per nucleus)Nuclear binding energy:1063.88321817 MeV (per nucleus) 8.4435176 MeV (average binding energy per nucleon)Separation energy:SN = 10.025(4) MeV (first neutron) SP = 7.599(4) MeV (first proton)Half-life:stableSpin and parity: (nuclear angular momentum)0+Charge radius:4.7722(52) femtometer fmYear of discovery:1922
Comparison of the natural Xenon isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):
Atomic Mass ma
Quantity
Half-life
Spin
Xenon Isotopic mixture
131.293 u
100 %
Isotope 124Xe
123.90589(2) u
0.095(5) %
> 1.8 × 1022 years
0+
Isotope 126Xe
125.90430(3) u
0.089(3) %
stable
0+
Isotope 128Xe
127.903531(7) u
1.910(13) %
stable
0+
Isotope 129Xe
128.90478086(4) u
26.401(138) %
stable
1/2+
Isotope 130Xe
129.9035094(1) u
4.071(22) %
stable
0+
Isotope 131Xe
130.905084(2) u
21.232(51) %
stable
3/2+
Isotope 132Xe
131.90415509(4) u
26.909(55) %
stable
0+
Isotope 134Xe
133.905393033(10) u
10.436(35) %
5.8 × 1022 years
0+
Isotope 136Xe
135.90721448(7) u
8.857(72) %
2.165(61) × 1021 years
0+
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 72) and isobaric (same nucleon number A = 126) with Xenon-126. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
