Molybdenum-99

Properties and data of the isotope ⁹⁹Mo.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

See also: List of individual Molybdenum isotopes (and general data sources).

General data

Name of the isotope:Molybdenum-99; Mo-99Symbol:⁹⁹Mo or 9942MoMass number A:99 (= number of nucleons)Atomic number Z:42 (= number of protons)Neutrons N:57Isotopic mass:98.90770730(24) u (atomic weight of Molybdenum-99)Nuclide mass:98.884668 u (calculated nuclear mass without electrons)Mass excess:-85.9701 MeVMass defect:0.91484425600001 u (per nucleus)Nuclear binding energy:852.1719354 MeV (per nucleus)
8.60779733 MeV (average binding energy per nucleon)Separation energy:S_N = 5.92544(15) MeV (first neutron)
S_P = 9.734(5) MeV (first proton)Half-life:65.924(6) hDecay constant λ:2.920649285372 × 10^-6 s^-1Specific activity α:1.794751163161 × 10⁺¹⁶ Bq g^-1
485067.88193559 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = + 0.375(3)Nuclear g-factor:g_l = 0.75Year of discovery:1948

Radioactive Decay

Half-life T_½ = 65.924(6) h (hours) respectively 2.373264 × 10⁵ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	^99mTc	100 %	1.3578(9) MeV

Parent Nuclides

Direct parent isotope is: ⁹⁹Nb.

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
^99m1Mo	97.785(3) keV	15.5(2) μs	5/2+
^99m2Mo	684.10(19) keV	0.76(6) μs	11/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 57) and isobaric (same nucleon number A = 99) with Molybdenum-99. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 57	Isobar A = 99
32	⁸⁹Ge
33	⁹⁰As
34	⁹¹Se
35	⁹²Br
36	⁹³Kr	⁹⁹Kr
37	⁹⁴Rb	⁹⁹Rb
38	⁹⁵Sr	⁹⁹Sr
39	⁹⁶Y	⁹⁹Y
40	⁹⁷Zr	⁹⁹Zr
41	⁹⁸Nb	⁹⁹Nb
42	⁹⁹Mo	⁹⁹Mo
43	¹⁰⁰Tc	⁹⁹Tc
44	¹⁰¹Ru	⁹⁹Ru
45	¹⁰²Rh	⁹⁹Rh
46	¹⁰³Pd	⁹⁹Pd
47	¹⁰⁴Ag	⁹⁹Ag
48	¹⁰⁵Cd	⁹⁹Cd
49	¹⁰⁶In	⁹⁹In
50	¹⁰⁷Sn	⁹⁹Sn
51	¹⁰⁸Sb
52	¹⁰⁹Te
53	¹¹⁰I
54	¹¹¹Xe
55	¹¹²Cs