Technetium-121

Properties and data of the isotope ¹²¹Tc.

Contents

See also: List of individual Technetium isotopes (and general data sources).

General data

Name of the isotope:Technetium-121; Tc-121Symbol:¹²¹Tc or 12143TcMass number A:121 (= number of nucleons)Atomic number Z:43 (= number of protons)Neutrons N:78Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.8139534883721 (= neutron-proton ratio)Neutron excess (N-Z):35Isotopic mass:120.96588(54) u (atomic weight of Technetium-121)Nuclide mass:120.9422922 u (calculated nuclear mass without electrons)Mass excess:-31.78258 MeVMass defect:1.046459824 u (per nucleus)Nuclear binding energy:974.7710473 MeV (per nucleus)
8.05595907 MeV (average binding energy per nucleon)Separation energy:S_N = 4.33(71) MeV (first neutron)Half-life:22(6) msDecay constant λ:31.506690025452 s^-1Specific activity α:1.581147711363 × 10⁺²³ Bq g^-1
4273372192874.6 Ci g^-1Spin and parity:
(nuclear angular momentum)

Radioactive Decay

Half-life T_½ = 22(6) ms respectively 2.2 × 10^-2 seconds s.

Decay mode	Daughter	Decay energy
β^-	¹²¹Ru	13.27(64) MeV
β^-, n	¹²⁰Ru	10.16(64) MeV
β^-, 2n	¹¹⁹Ru

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 121) with Technetium-121. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 78	Isobar A = 121
43	¹²¹Tc	¹²¹Tc
44	¹²²Ru	¹²¹Ru
45	¹²³Rh	¹²¹Rh
46	¹²⁴Pd	¹²¹Pd
47	¹²⁵Ag	¹²¹Ag
48	¹²⁶Cd	¹²¹Cd
49	¹²⁷In	¹²¹In
50	¹²⁸Sn	¹²¹Sn
51	¹²⁹Sb	¹²¹Sb
52	¹³⁰Te	¹²¹Te
53	¹³¹I	¹²¹I
54	¹³²Xe	¹²¹Xe
55	¹³³Cs	¹²¹Cs
56	¹³⁴Ba	¹²¹Ba
57	¹³⁵La	¹²¹La
58	¹³⁶Ce	¹²¹Ce
59	¹³⁷Pr	¹²¹Pr
60	¹³⁸Nd
61	¹³⁹Pm
62	¹⁴⁰Sm
63	¹⁴¹Eu
64	¹⁴²Gd
65	¹⁴³Tb
66	¹⁴⁴Dy
67	¹⁴⁵Ho
68	¹⁴⁶Er
69	¹⁴⁷Tm
70	¹⁴⁸Yb
71	¹⁴⁹Lu