Krypton-99

Properties and data of the isotope ⁹⁹Kr.

Content

General data

Name of the isotope:Krypton-99; Kr-99Symbol:⁹⁹Kr or 9936KrMass number A:99 (= number of nucleons)Atomic number Z:36 (= number of protons)Neutrons N:63Isotopic mass:98.95839(43) u (atomic weight of Krypton-99)Nuclide mass:98.9386419 u (calculated nuclear mass without electrons)Mass excess:-38.75947 MeVMass defect:0.86920086000001 u (per nucleus)Nuclear binding energy:809.65538588 MeV (per nucleus)
8.17833723 MeV (average binding energy per nucleon)Separation energy:S_N = 2.52(50) MeV (first neutron)
S_P = 17.80(57) MeV (first proton)Half-life:13 msDecay constant λ:53.319013889227 s^-1Specific activity α:3.276475634222 × 10⁺²³ Bq g^-1
8855339551953.8 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1997

Radioactive Decay

Half-life T_½ = 13 ms respectively 1.3 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁹⁹Rb	89 %	12.36(40) MeV
β^-, n	⁹⁸Rb	11(7) %	7.54(40) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 63) and isobaric (same nucleon number A = 99) with Krypton-99. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 63	Isobar A = 99
35	⁹⁸Br
36	⁹⁹Kr	⁹⁹Kr
37	¹⁰⁰Rb	⁹⁹Rb
38	¹⁰¹Sr	⁹⁹Sr
39	¹⁰²Y	⁹⁹Y
40	¹⁰³Zr	⁹⁹Zr
41	¹⁰⁴Nb	⁹⁹Nb
42	¹⁰⁵Mo	⁹⁹Mo
43	¹⁰⁶Tc	⁹⁹Tc
44	¹⁰⁷Ru	⁹⁹Ru
45	¹⁰⁸Rh	⁹⁹Rh
46	¹⁰⁹Pd	⁹⁹Pd
47	¹¹⁰Ag	⁹⁹Ag
48	¹¹¹Cd	⁹⁹Cd
49	¹¹²In	⁹⁹In
50	¹¹³Sn	⁹⁹Sn
51	¹¹⁴Sb
52	¹¹⁵Te
53	¹¹⁶I
54	¹¹⁷Xe
55	¹¹⁸Cs
56	¹¹⁹Ba
57	¹²⁰La
58	¹²¹Ce
59	¹²²Pr