Krypton-85

Properties and data of the isotope ⁸⁵Kr.

Content

General data

Name of the isotope:Krypton-85; Kr-85Symbol:⁸⁵Kr or 8536KrMass number A:85 (= number of nucleons)Atomic number Z:36 (= number of protons)Neutrons N:49Isotopic mass:84.9125273(21) u (atomic weight of Krypton-85)Nuclide mass:84.8927792 u (calculated nuclear mass without electrons)Mass excess:-81.4803 MeVMass defect:0.79375473600001 u (per nucleus)Nuclear binding energy:739.37777406 MeV (per nucleus)
8.69856205 MeV (average binding energy per nucleon)Separation energy:S_N = 7.1123(20) MeV (first neutron)
S_P = 10.986(26) MeV (first proton)Half-life:10.739(14) aDecay constant λ:2.046703874633 × 10^-9 s^-1Specific activity α:14673260751930 Bq g^-1
396.57461491703 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2+Magnetic dipole moment:μ(μ_N) = - 1.0055(4)Quadrupole moment Q:+ 0.443(3) barn (100 fm²)Nuclear g-factor:g_l = -0.22344444444444Charge radius:4.1846(22) femtometer fmYear of discovery:1940

Radioactive Decay

Half-life T_½ = 10.739(14) a respectively 3.38665104 × 10⁸ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁸⁵Rb	100 %	0.687(2) MeV

Parent Nuclides

Direct parent isotope is: ⁸⁵Br.

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
^85m1Kr	304.871(20) keV	4.480(8) h	1/2-
^85m2Kr	1991.8(2) keV	1.82(5) μs	(17/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 49) and isobaric (same nucleon number A = 85) with Krypton-85. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 49	Isobar A = 85
27	⁷⁶Co
28	⁷⁷Ni
29	⁷⁸Cu
30	⁷⁹Zn	⁸⁵Zn
31	⁸⁰Ga	⁸⁵Ga
32	⁸¹Ge	⁸⁵Ge
33	⁸²As	⁸⁵As
34	⁸³Se	⁸⁵Se
35	⁸⁴Br	⁸⁵Br
36	⁸⁵Kr	⁸⁵Kr
37	⁸⁶Rb	⁸⁵Rb
38	⁸⁷Sr	⁸⁵Sr
39	⁸⁸Y	⁸⁵Y
40	⁸⁹Zr	⁸⁵Zr
41	⁹⁰Nb	⁸⁵Nb
42	⁹¹Mo	⁸⁵Mo
43	⁹²Tc	⁸⁵Tc
44	⁹³Ru	⁸⁵Ru
45	⁹⁴Rh
46	⁹⁵Pd
47	⁹⁶Ag
48	⁹⁷Cd
49	⁹⁸In
50	⁹⁹Sn