Zirconium-99

Properties and data of the isotope ⁹⁹Zr.

Content

General data

Name of the isotope:Zirconium-99; Zr-99Symbol:⁹⁹Zr or 9940ZrMass number A:99 (= number of nucleons)Atomic number Z:40 (= number of protons)Neutrons N:59Isotopic mass:98.916671(11) u (atomic weight of Zirconium-99)Nuclide mass:98.8947288 u (calculated nuclear mass without electrons)Mass excess:-77.62046 MeVMass defect:0.907560324 u (per nucleus)Nuclear binding energy:845.38699644 MeV (per nucleus)
8.53926259 MeV (average binding energy per nucleon)Separation energy:S_N = 4.405(13) MeV (first neutron)
S_P = 12.615(13) MeV (first proton)Half-life:2.1(1) sDecay constant λ:0.33007008598093 s^-1Specific activity α:2.028294440233 × 10⁺²¹ Bq g^-1
54818768654.951 Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2+)Magnetic dipole moment:μ(μ_N) = - 0.929(4)Nuclear g-factor:g_l = -1.858Charge radius:4.4156(181) femtometer fmYear of discovery:1970

Radioactive Decay

Half-life T_½ = 2.1(1) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁹⁹Nb	100 %	4.715(16) MeV

Parent Nuclides

Direct parent isotopes are: ⁹⁹Y, ¹⁰⁰Y.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 59) and isobaric (same nucleon number A = 99) with Zirconium-99. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 59	Isobar A = 99
33	⁹²As
34	⁹³Se
35	⁹⁴Br
36	⁹⁵Kr	⁹⁹Kr
37	⁹⁶Rb	⁹⁹Rb
38	⁹⁷Sr	⁹⁹Sr
39	⁹⁸Y	⁹⁹Y
40	⁹⁹Zr	⁹⁹Zr
41	¹⁰⁰Nb	⁹⁹Nb
42	¹⁰¹Mo	⁹⁹Mo
43	¹⁰²Tc	⁹⁹Tc
44	¹⁰³Ru	⁹⁹Ru
45	¹⁰⁴Rh	⁹⁹Rh
46	¹⁰⁵Pd	⁹⁹Pd
47	¹⁰⁶Ag	⁹⁹Ag
48	¹⁰⁷Cd	⁹⁹Cd
49	¹⁰⁸In	⁹⁹In
50	¹⁰⁹Sn	⁹⁹Sn
51	¹¹⁰Sb
52	¹¹¹Te
53	¹¹²I
54	¹¹³Xe
55	¹¹⁴Cs
56	¹¹⁵Ba
57	¹¹⁶La