Ruthenium-121

Properties and data of the isotope ¹²¹Ru.

Content

General data

Name of the isotope:Ruthenium-121; Ru-121Symbol:¹²¹Ru or 12144RuMass number A:121 (= number of nucleons)Atomic number Z:44 (= number of protons)Neutrons N:77Isotopic mass:120.95164(43) u (atomic weight of Ruthenium-121)Nuclide mass:120.9275037 u (calculated nuclear mass without electrons)Mass excess:-45.04705 MeVMass defect:1.05985994 u (per nucleus)Nuclear binding energy:987.25317495 MeV (per nucleus)
8.15911715 MeV (average binding energy per nucleon)Separation energy:S_N = 3.11(57) MeV (first neutron)
S_P = 16.82(64) MeV (first proton)Half-life:29(2) msDecay constant λ:23.90162691586 s^-1Specific activity α:1.199491367241 × 10⁺²³ Bq g^-1
3241868560111.9 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:2010

Radioactive Decay

Half-life T_½ = 29(2) ms respectively 2.9 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	¹²¹Rh		11.20(74) MeV
β^-, n	¹²⁰Rh	?	5.70(45) MeV
β^-, 2n	¹¹⁹Rh	?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 77) and isobaric (same nucleon number A = 121) with Ruthenium-121. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 77	Isobar A = 121
43	¹²⁰Tc	¹²¹Tc
44	¹²¹Ru	¹²¹Ru
45	¹²²Rh	¹²¹Rh
46	¹²³Pd	¹²¹Pd
47	¹²⁴Ag	¹²¹Ag
48	¹²⁵Cd	¹²¹Cd
49	¹²⁶In	¹²¹In
50	¹²⁷Sn	¹²¹Sn
51	¹²⁸Sb	¹²¹Sb
52	¹²⁹Te	¹²¹Te
53	¹³⁰I	¹²¹I
54	¹³¹Xe	¹²¹Xe
55	¹³²Cs	¹²¹Cs
56	¹³³Ba	¹²¹Ba
57	¹³⁴La	¹²¹La
58	¹³⁵Ce	¹²¹Ce
59	¹³⁶Pr	¹²¹Pr
60	¹³⁷Nd
61	¹³⁸Pm
62	¹³⁹Sm
63	¹⁴⁰Eu
64	¹⁴¹Gd
65	¹⁴²Tb
66	¹⁴³Dy
67	¹⁴⁴Ho
68	¹⁴⁵Er
69	¹⁴⁶Tm