Xenon-126

Properties and data of the isotope ¹²⁶Xe.

Contents

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:72Isotopic 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:S_N = 10.025(4) MeV (first neutron)
S_P = 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

Parent Nuclides

Direct parent isotopes are: ¹²⁶Cs, ¹²⁶I.

Occurrence

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

	Atomic Mass m_a	Quantity	Half-life	Spin
Xenon Isotopic mixture	131.293 u	100 %
Isotope ¹²⁴Xe	123.90589(2) u	0.095(5) %	> 1.8 × 10²² a	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 a	0+
Isotope ¹³⁶Xe	135.90721448(7) u	8.857(72) %	2.165(61) × 10²¹ a	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.

Z	Isotone N = 72	Isobar A = 126
40	¹¹²Zr
41	¹¹³Nb
42	¹¹⁴Mo
43	¹¹⁵Tc
44	¹¹⁶Ru
45	¹¹⁷Rh	¹²⁶Rh
46	¹¹⁸Pd	¹²⁶Pd
47	¹¹⁹Ag	¹²⁶Ag
48	¹²⁰Cd	¹²⁶Cd
49	¹²¹In	¹²⁶In
50	¹²²Sn	¹²⁶Sn
51	¹²³Sb	¹²⁶Sb
52	¹²⁴Te	¹²⁶Te
53	¹²⁵I	¹²⁶I
54	¹²⁶Xe	¹²⁶Xe
55	¹²⁷Cs	¹²⁶Cs
56	¹²⁸Ba	¹²⁶Ba
57	¹²⁹La	¹²⁶La
58	¹³⁰Ce	¹²⁶Ce
59	¹³¹Pr	¹²⁶Pr
60	¹³²Nd	¹²⁶Nd
61	¹³³Pm	¹²⁶Pm
62	¹³⁴Sm
63	¹³⁵Eu
64	¹³⁶Gd
65	¹³⁷Tb
66	¹³⁸Dy