Ruthenium-123

Properties and data of the isotope ¹²³Ru.

Content

General data

Name of the isotope:Ruthenium-123; Ru-123Symbol:¹²³Ru or 12344RuMass number A:123 (= number of nucleons)Atomic number Z:44 (= number of protons)Neutrons N:79Isotopic mass:122.96019(54) u (atomic weight of Ruthenium-123)Nuclide mass:122.9360537 u (calculated nuclear mass without electrons)Mass excess:-37.08278 MeVMass defect:1.068639772 u (per nucleus)Nuclear binding energy:995.43153578 MeV (per nucleus)
8.09293932 MeV (average binding energy per nucleon)Separation energy:S_N = 3.00(71) MeV (first neutron)Half-life:19(2) msDecay constant λ:36.481430555787 s^-1Specific activity α:1.800789455565 × 10⁺²³ Bq g^-1
4866998528554.3 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:2010

Radioactive Decay

Half-life T_½ = 19(2) ms respectively 1.9 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	¹²³Rh		12.28(64) MeV
β^-, n	¹²²Rh	?	6.93(58) MeV
β^-, 2n	¹²¹Rh	?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 79) and isobaric (same nucleon number A = 123) with Ruthenium-123. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 79	Isobar A = 123
44	¹²³Ru	¹²³Ru
45	¹²⁴Rh	¹²³Rh
46	¹²⁵Pd	¹²³Pd
47	¹²⁶Ag	¹²³Ag
48	¹²⁷Cd	¹²³Cd
49	¹²⁸In	¹²³In
50	¹²⁹Sn	¹²³Sn
51	¹³⁰Sb	¹²³Sb
52	¹³¹Te	¹²³Te
53	¹³²I	¹²³I
54	¹³³Xe	¹²³Xe
55	¹³⁴Cs	¹²³Cs
56	¹³⁵Ba	¹²³Ba
57	¹³⁶La	¹²³La
58	¹³⁷Ce	¹²³Ce
59	¹³⁸Pr	¹²³Pr
60	¹³⁹Nd
61	¹⁴⁰Pm
62	¹⁴¹Sm
63	¹⁴²Eu
64	¹⁴³Gd
65	¹⁴⁴Tb
66	¹⁴⁵Dy
67	¹⁴⁶Ho
68	¹⁴⁷Er
69	¹⁴⁸Tm
70	¹⁴⁹Yb
71	¹⁵⁰Lu