Indium-121
Properties and data of the isotope 121In.
See also: List of individual Indium isotopes (and general data sources).
General data
Name of the isotope:Indium-121; In-121Symbol:121In or 12149InMass number A:121 (= number of nucleons)Atomic number Z:49 (= number of protons)Neutrons N:72Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.469387755102 (= neutron-proton ratio)Neutron excess (N-Z):23Isotopic mass:120.907851(29) u (atomic weight of Indium-121)Nuclide mass:120.8809721 u (calculated nuclear mass without electrons)Mass excess:-85.83624 MeVMass defect:1.09944952 u (per nucleus)Nuclear binding energy:1024.13063118 MeV (per nucleus)
8.46388951 MeV (average binding energy per nucleon)Separation energy:SN = 8.18(5) MeV (first neutron)
SP = 9.168(28) MeV (first proton)Half-life:23.1(6) sDecay constant λ:0.030006371452811 s-1Specific activity α:1.505854963203 × 10+20 Bq g-1
4069878278.9284 Ci g-1Spin and parity:
(nuclear angular momentum)9/2+Magnetic dipole moment:μ(μN) = +5.494(5)Quadrupole moment Q:+ 0.814(11) barn (100 fm2)Nuclear g-factor:gl = 1.2208888888889Charge radius:4.6505(47) femtometer fmYear of discovery:1960
Radioactive Decay
Half-life T½ = 23.1(6) s respectively 2.31 × 101 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β- | 121Sn | 100 % | 3.361(27) MeV | |
Parent Nuclides
Direct parent isotope is: 121Cd.
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 |
|---|
| 121mIn | 313.68(7) keV | 3.88(10) min | 1/2- |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 72) and isobaric (same nucleon number A = 121) with Indium-121. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 72 | Isobar A = 121 |
|---|
| 40 | 112Zr | |
| 41 | 113Nb | |
| 42 | 114Mo | |
| 43 | 115Tc | 121Tc |
| 44 | 116Ru | 121Ru |
| 45 | 117Rh | 121Rh |
| 46 | 118Pd | 121Pd |
| 47 | 119Ag | 121Ag |
| 48 | 120Cd | 121Cd |
| 49 | 121In | 121In |
| 50 | 122Sn | 121Sn |
| 51 | 123Sb | 121Sb |
| 52 | 124Te | 121Te |
| 53 | 125I | 121I |
| 54 | 126Xe | 121Xe |
| 55 | 127Cs | 121Cs |
| 56 | 128Ba | 121Ba |
| 57 | 129La | 121La |
| 58 | 130Ce | 121Ce |
| 59 | 131Pr | 121Pr |
| 60 | 132Nd | |
| 61 | 133Pm | |
| 62 | 134Sm | |
| 63 | 135Eu | |
| 64 | 136Gd | |
| 65 | 137Tb | |
| 66 | 138Dy | |
External data and identifiers
Last update: 2020-10-17
Perma link: https://www.chemlin.org/isotope/indium-121
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