Cesium-128
Properties and data of the isotope 128Cs.
See also: List of individual Cesium isotopes (and general data sources).
General data
Name of the isotope:Cesium-128; Cs-128Symbol:128Cs or 12855CsMass number A:128 (= number of nucleons)Atomic number Z:55 (= number of protons)Neutrons N:73Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.3272727272727 (= neutron-proton ratio)Neutron excess (N-Z):18Isotopic mass:127.907749(6) u (atomic weight of Cesium-128)Nuclide mass:127.8775791 u (calculated nuclear mass without electrons)Mass excess:-85.93125 MeVMass defect:1.155166628 u (per nucleus)Nuclear binding energy:1076.03078298 MeV (per nucleus)
8.40649049 MeV (average binding energy per nucleon)Separation energy:SN = 7.763(8) MeV (first neutron)
SP = 4.899(7) MeV (first proton)Half-life:3.640(14) minDecay constant λ:0.0031737508267397 s-1Specific activity α:1.504942876611 × 10+19 Bq g-1
406741318.00314 Ci g-1Spin and parity:
(nuclear angular momentum)1+Magnetic dipole moment:μ(μN) = + 0.972(5)Quadrupole moment Q:- 0.570(8) barn (100 fm2)Nuclear g-factor:gl = 0.972Charge radius:4.7921(52) femtometer fmYear of discovery:1951
Radioactive Decay
Half-life T½ = 3.640(14) min (minutes) respectively 2.184 × 102 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| EC/β+ | 128Xe | 100 % | 3.929(6) MeV | |
Parent Nuclides
Direct parent isotope is: 128Ba.
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 73) and isobaric (same nucleon number A = 128) with Cesium-128. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 73 | Isobar A = 128 |
|---|
| 41 | 114Nb | |
| 42 | 115Mo | |
| 43 | 116Tc | |
| 44 | 117Ru | |
| 45 | 118Rh | |
| 46 | 119Pd | 128Pd |
| 47 | 120Ag | 128Ag |
| 48 | 121Cd | 128Cd |
| 49 | 122In | 128In |
| 50 | 123Sn | 128Sn |
| 51 | 124Sb | 128Sb |
| 52 | 125Te | 128Te |
| 53 | 126I | 128I |
| 54 | 127Xe | 128Xe |
| 55 | 128Cs | 128Cs |
| 56 | 129Ba | 128Ba |
| 57 | 130La | 128La |
| 58 | 131Ce | 128Ce |
| 59 | 132Pr | 128Pr |
| 60 | 133Nd | 128Nd |
| 61 | 134Pm | 128Pm |
| 62 | 135Sm | 128Sm |
| 63 | 136Eu | |
| 64 | 137Gd | |
| 65 | 138Tb | |
| 66 | 139Dy | |
| 67 | 140Ho | |
External data and identifiers
Last update: 2020-10-18
Perma link: https://www.chemlin.org/isotope/cesium-128
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