Promethium-131

Properties and data of the isotope ¹³¹Pm.

Content

General data

Name of the isotope:Promethium-131; Pm-131Symbol:¹³¹Pm or 13161PmMass number A:131 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:70Isotopic mass:130.93595(21) u (atomic weight of Promethium-131)Nuclide mass:130.9024892 u (calculated nuclear mass without electrons)Mass excess:-59.66219 MeVMass defect:1.147921072 u (per nucleus)Nuclear binding energy:1069.28159104 MeV (per nucleus)
8.16245489 MeV (average binding energy per nucleon)Separation energy:S_N = 12.34(28) MeV (first neutron)
S_P = 0.35(20) MeV (first proton)Half-life:6.3(8) sDecay constant λ:0.11002336199364 s^-1Specific activity α:5.096739875457 × 10⁺²⁰ Bq g^-1
13774972636.373 Ci g^-1Spin and parity:
(nuclear angular momentum)(11/2-)Year of discovery:1998

Radioactive Decay

Half-life T_½ = 6.3(8) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³¹Nd	100 %	8.11(20) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 70) and isobaric (same nucleon number A = 131) with Promethium-131. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 70	Isobar A = 131
39	¹⁰⁹Y
40	¹¹⁰Zr
41	¹¹¹Nb
42	¹¹²Mo
43	¹¹³Tc
44	¹¹⁴Ru
45	¹¹⁵Rh
46	¹¹⁶Pd
47	¹¹⁷Ag	¹³¹Ag
48	¹¹⁸Cd	¹³¹Cd
49	¹¹⁹In	¹³¹In
50	¹²⁰Sn	¹³¹Sn
51	¹²¹Sb	¹³¹Sb
52	¹²²Te	¹³¹Te
53	¹²³I	¹³¹I
54	¹²⁴Xe	¹³¹Xe
55	¹²⁵Cs	¹³¹Cs
56	¹²⁶Ba	¹³¹Ba
57	¹²⁷La	¹³¹La
58	¹²⁸Ce	¹³¹Ce
59	¹²⁹Pr	¹³¹Pr
60	¹³⁰Nd	¹³¹Nd
61	¹³¹Pm	¹³¹Pm
62	¹³²Sm	¹³¹Sm
63	¹³³Eu	¹³¹Eu
64	¹³⁴Gd
65	¹³⁵Tb