Tellurium-121m

Properties and data of the isotope ¹²¹Te.

Content

General data

Name of the isotope:Tellurium-121m; Te-121mSymbol:¹²¹Te or 12152TeMass number A:121 (= number of nucleons)Atomic number Z:52 (= number of protons)Neutrons N:69Isotopic mass:120.904945(28) u (atomic weight of Tellurium-121m)
Excitation energy: 293.974(22) keVNuclide mass:120.8764206 u (calculated nuclear mass without electrons)Mass excess:-88.54316 MeVMass defect:1.099835868 u (per nucleus)Nuclear binding energy:1024.49051203 MeV (per nucleus)
8.46686374 MeV (average binding energy per nucleon)Half-life:164.2(8) dDecay constant λ:4.885832406843 × 10^-8 s^-1Specific activity α:2.451930914337 × 10⁺¹⁴ Bq g^-1
6626.8403090211 Ci g^-1Spin and parity:
(nuclear angular momentum)11/2-Magnetic dipole moment:μ(μ_N) = 0.895(10)Nuclear g-factor:g_l = 0.16272727272727

Radioactive Decay

Half-life T_½ = 164.2(8) d respectively 1.4186880 × 10⁷ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹²¹Sb	11.4(11) %
Iso	¹²¹Te	88.6(11) %

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
¹²¹Te		19.17(4) d	1/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 69) and isobaric (same nucleon number A = 121) with Tellurium-121m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 69	Isobar A = 121
38	¹⁰⁷Sr
39	¹⁰⁸Y
40	¹⁰⁹Zr
41	¹¹⁰Nb
42	¹¹¹Mo
43	¹¹²Tc	¹²¹Tc
44	¹¹³Ru	¹²¹Ru
45	¹¹⁴Rh	¹²¹Rh
46	¹¹⁵Pd	¹²¹Pd
47	¹¹⁶Ag	¹²¹Ag
48	¹¹⁷Cd	¹²¹Cd
49	¹¹⁸In	¹²¹In
50	¹¹⁹Sn	¹²¹Sn
51	¹²⁰Sb	¹²¹Sb
52	¹²¹Te	¹²¹Te
53	¹²²I	¹²¹I
54	¹²³Xe	¹²¹Xe
55	¹²⁴Cs	¹²¹Cs
56	¹²⁵Ba	¹²¹Ba
57	¹²⁶La	¹²¹La
58	¹²⁷Ce	¹²¹Ce
59	¹²⁸Pr	¹²¹Pr
60	¹²⁹Nd
61	¹³⁰Pm
62	¹³¹Sm
63	¹³²Eu