Technetium-99m

Properties and data of the isotope ^99mTc.

Contents

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

General data

Name of the isotope:Technetium-99m; Tc-99mSymbol:^99mTc or 99m43TcMass number A:99 (= number of nucleons)Atomic number Z:43 (= number of protons)Neutrons N:56Isotopic mass:98.9062547(21) u (atomic weight of Technetium-99m)
Excitation energy: 142.6836(11) keVNuclide mass:98.8826669 u (calculated nuclear mass without electrons)Mass excess:-87.32318 MeVMass defect:0.915456972 u (per nucleus)Nuclear binding energy:852.74267668 MeV (per nucleus)
8.61356239 MeV (average binding energy per nucleon)Half-life:6.0072(9) hDecay constant λ:3.205168522587 × 10^-5 s^-1Specific activity α:1.969589420699 × 10⁺¹⁷ Bq g^-1
5323214.6505397 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Year of discovery:1938

Radioactive Decay

Half-life T_½ = 6.0072(9) h (hours) respectively 2.162592 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁹⁹Ru	0.0037(6) %	0.4402(9) MeV	0.140511(1) MeV 89(4) %
Iso	⁹⁹Tc	99.9963(6) %	0.1426836(11) MeV

Occurrence

Comparison of the natural Technetium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Technetium Isotopic mixture	98.9062547 u	100 %
Isotope ⁹⁹Tc	98.9062547(21) u		6.0072(9) h	1/2-

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
⁹⁹Tc		2.111(12) × 10⁵ a	9/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 56) and isobaric (same nucleon number A = 99) with Technetium-99m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 56	Isobar A = 99
31	⁸⁷Ga
32	⁸⁸Ge
33	⁸⁹As
34	⁹⁰Se
35	⁹¹Br
36	⁹²Kr	⁹⁹Kr
37	⁹³Rb	⁹⁹Rb
38	⁹⁴Sr	⁹⁹Sr
39	⁹⁵Y	⁹⁹Y
40	⁹⁶Zr	⁹⁹Zr
41	⁹⁷Nb	⁹⁹Nb
42	⁹⁸Mo	⁹⁹Mo
43	⁹⁹Tc	⁹⁹Tc
44	¹⁰⁰Ru	⁹⁹Ru
45	¹⁰¹Rh	⁹⁹Rh
46	¹⁰²Pd	⁹⁹Pd
47	¹⁰³Ag	⁹⁹Ag
48	¹⁰⁴Cd	⁹⁹Cd
49	¹⁰⁵In	⁹⁹In
50	¹⁰⁶Sn	⁹⁹Sn
51	¹⁰⁷Sb
52	¹⁰⁸Te
53	¹⁰⁹I
54	¹¹⁰Xe