Xenon-121

Properties and data of the isotope ¹²¹Xe.

Content

General data

Name of the isotope:Xenon-121; Xe-121Symbol:¹²¹Xe or 12154XeMass number A:121 (= number of nucleons)Atomic number Z:54 (= number of protons)Neutrons N:67Isotopic mass:120.911453(11) u (atomic weight of Xenon-121)Nuclide mass:120.8818316 u (calculated nuclear mass without electrons)Mass excess:-82.481 MeVMass defect:1.0916481 u (per nucleus)Nuclear binding energy:1016.86365526 MeV (per nucleus)
8.40383186 MeV (average binding energy per nucleon)Separation energy:S_N = 8.380(16) MeV (first neutron)
S_P = 6.017(18) MeV (first proton)Half-life:40.1(20) minDecay constant λ:0.00028809109748959 s^-1Specific activity α:1.445770974646 × 10⁺¹⁸ Bq g^-1
39074891.206668 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2(+)Magnetic dipole moment:μ(μ_N) = - 0.701(3)Quadrupole moment Q:+ 0.0133(5) barn (100 fm²)Nuclear g-factor:g_l = -0.2804Year of discovery:1952

Radioactive Decay

Half-life T_½ = 40.1(20) min (minutes) respectively 2.406 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹²¹I	100 %	3.770(12) MeV

Parent Nuclides

Direct parent isotope is: ¹²¹Cs.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 67) and isobaric (same nucleon number A = 121) with Xenon-121. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 67	Isobar A = 121
38	¹⁰⁵Sr
39	¹⁰⁶Y
40	¹⁰⁷Zr
41	¹⁰⁸Nb
42	¹⁰⁹Mo
43	¹¹⁰Tc	¹²¹Tc
44	¹¹¹Ru	¹²¹Ru
45	¹¹²Rh	¹²¹Rh
46	¹¹³Pd	¹²¹Pd
47	¹¹⁴Ag	¹²¹Ag
48	¹¹⁵Cd	¹²¹Cd
49	¹¹⁶In	¹²¹In
50	¹¹⁷Sn	¹²¹Sn
51	¹¹⁸Sb	¹²¹Sb
52	¹¹⁹Te	¹²¹Te
53	¹²⁰I	¹²¹I
54	¹²¹Xe	¹²¹Xe
55	¹²²Cs	¹²¹Cs
56	¹²³Ba	¹²¹Ba
57	¹²⁴La	¹²¹La
58	¹²⁵Ce	¹²¹Ce
59	¹²⁶Pr	¹²¹Pr
60	¹²⁷Nd
61	¹²⁸Pm
62	¹²⁹Sm
63	¹³⁰Eu