Yttrium-99
Properties and data of the isotope 99Y.
See also: list of Yttrium isotopes.
General data
Name of the isotope:Yttrium-99; Y-99Symbol:99Y or 9939YMass number A:99 (= number of nucleons)Atomic number Z:39 (= number of protons)Neutrons N:60Isotopic mass:98.924154(7) u (atomic weight of Yttrium-99)Nuclide mass:98.9027603 u (calculated nuclear mass without electrons)Mass excess:-70.65009 MeVMass defect:0.900917208 u (per nucleus)Nuclear binding energy:839.19897375 MeV (per nucleus)
8.47675731 MeV (average binding energy per nucleon)Separation energy:SN = 6.426(10) MeV (first neutron)
SP = 11.516(7) MeV (first proton)Half-life:1.484(7) sDecay constant λ:0.46708031035037 s-1Specific activity α:2.870227981462 × 10+21 Bq g-1
77573729228.705 Ci g-1Spin and parity:
(nuclear angular momentum)(5/2+)Magnetic dipole moment:μ(μN) = +3.18(2)Quadrupole moment Q:+1.55(17) barn (100 fm2)Nuclear g-factor:gl = 1.272Charge radius:4.4658(223) femtometer fmYear of discovery:1975
Radioactive Decay
Half-life T½ = 1.484(7) s.
| Decay mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β- | 99Zr | 98.3 % | 7.57 MeV | |
| β-, n | 98Zr | 1.77(19) % | ? | |
Parent Nuclides
Direct parent isotope is: 99Sr.
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 |
|---|
| 99mY | 2141.65(19) keV | 8.0(5) μs | (17/2+) |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 60) and isobaric (same nucleon number A = 99) with Yttrium-99. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| OZ | Isotone N = 60 | Isobar A = 99 |
|---|
| 34 | 94Se | |
| 35 | 95Br | |
| 36 | 96Kr | 99Kr |
| 37 | 97Rb | 99Rb |
| 38 | 98Sr | 99Sr |
| 39 | 99Y | 99Y |
| 40 | 100Zr | 99Zr |
| 41 | 101Nb | 99Nb |
| 42 | 102Mo | 99Mo |
| 43 | 103Tc | 99Tc |
| 44 | 104Ru | 99Ru |
| 45 | 105Rh | 99Rh |
| 46 | 106Pd | 99Pd |
| 47 | 107Ag | 99Ag |
| 48 | 108Cd | 99Cd |
| 49 | 109In | 99In |
| 50 | 110Sn | 99Sn |
| 51 | 111Sb | |
| 52 | 112Te | |
| 53 | 113I | |
| 54 | 114Xe | |
| 55 | 115Cs | |
| 56 | 116Ba | |
| 57 | 117La | |
External data and identifiers
Last update: 2020-10-14
Perma link: https://www.chemlin.org/isotope/yttrium-99
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