Potassium-50

Properties and data of the isotope ⁵⁰K.

Contents

Potassium-50 is a radioisotope of the chemical element potassium, which has 31 neutrons in its atomic nucleus in addition to the element-specific 19 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 50. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ⁵⁰K is exclusively for academic purposes.

The discovery of the isotope was reported in 1972[1]; according to this report, potassium-50 was produced and identified as a fragmentation product during the irradiation of uranium templates with high-energy protons of an energy of 24 GeV.

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

General data

Name of the isotope:Potassium-50; K-50Symbol:⁵⁰K or 5019KMass number A:50 (= number of nucleons)Atomic number Z:19 (= number of protons)Neutrons N:31Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.6315789473684 (= neutron-proton ratio)Neutron excess (N-Z):12Isotopic mass:49.972380(8) u (atomic weight of Potassium-50)Nuclide mass:49.9619572 u (calculated nuclear mass without electrons)Mass excess:-25.72786 MeVMass defect:0.444908004 u (per nucleus)Nuclear binding energy:414.42913628 MeV (per nucleus)
8.28858273 MeV (average binding energy per nucleon)Separation energy:S_N = 4.188(8) MeV (first neutron)
S_P = 15.957(400) MeV (first proton)Half-life:472(4) msDecay constant λ:1.4685321622033 s^-1Specific activity α:1.804838273088 × 10⁺²² Bq g^-1
487794127861.86 Ci g^-1Spin and parity:
(nuclear angular momentum)0(-)Year of discovery:1972

Radioactive Decay

Half-life T_½ = 472(4) ms respectively 4.72 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	⁵⁰Ca	71(3) %	13.861(8) MeV
β^-, n	⁴⁹Ca	29(3) %	7.501(8) MeV
β^-, 2n ?	⁴⁸Ca

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
^50mK	172.0(4) keV	131(40) ns	(2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 31) and isobaric (same nucleon number A = 50) with Potassium-50. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 31	Isobar A = 50
15	⁴⁶P
16	⁴⁷S
17	⁴⁸Cl	⁵⁰Cl
18	⁴⁹Ar	⁵⁰Ar
19	⁵⁰K	⁵⁰K
20	⁵¹Ca	⁵⁰Ca
21	⁵²Sc	⁵⁰Sc
22	⁵³Ti	⁵⁰Ti
23	⁵⁴V	⁵⁰V
24	⁵⁵Cr	⁵⁰Cr
25	⁵⁶Mn	⁵⁰Mn
26	⁵⁷Fe	⁵⁰Fe
27	⁵⁸Co	⁵⁰Co
28	⁵⁹Ni	⁵⁰Ni
29	⁶⁰Cu
30	⁶¹Zn
31	⁶²Ga
32	⁶³Ge
33	⁶⁴As
34	⁶⁵Se
35	⁶⁶Br
36	⁶⁷Kr