Potassium-45
Properties and data of the isotope 45K.
Potassium-45 is a radioisotope of the chemical element potassium, which has 26 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 45. The short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of 45K is exclusively for academic purposes.
The radioactive nuclide was discovered during the irradiation of enriched calcium-48 samples (94%) with 52 MeV alpha particles (helium-4 nuclei) [1].
See also: List of individual Potassium isotopes (and general data sources).
General data
Name of the isotope:Potassium-45; K-45Symbol:45K or 4519KMass number A:45 (= number of nucleons)Atomic number Z:19 (= number of protons)Neutrons N:26Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3684210526316 (= neutron-proton ratio)Neutron excess (N-Z):7Isotopic mass:44.9606915(6) u (atomic weight of Potassium-45)Nuclide mass:44.9502687 u (calculated nuclear mass without electrons)Mass excess:-36.61563 MeVMass defect:0.41327192399999 u (per nucleus)Nuclear binding energy:384.96031757 MeV (per nucleus)
8.55467372 MeV (average binding energy per nucleon)Separation energy:SN = 8.9055(7) MeV (first neutron)
SP = 11.2314(17) MeV (first proton)Half-life:17.81(61) minDecay constant λ:0.00064864980400519 s-1Specific activity α:8.877864746567 × 10+18 Bq g-1
239942290.44776 Ci g-1Spin and parity:
(nuclear angular momentum)3/2+Magnetic dipole moment:μ(μN) = + 0.1734(8)Nuclear g-factor:gl = 0.1156Charge radius:3.4605(118) femtometer fmMirror nucleus:Iron-45Year of discovery:1964
Radioactive Decay
Half-life T½ = 17.81(61) min (minutes) respectively 1.0686 × 103 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| β- | 45Ca | 100 % | 4.1966(6) MeV | |
Parent Nuclides
Direct parent isotope is: 45Ar.
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 26) and isobaric (same nucleon number A = 45) with Potassium-45. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 26 | Isobar A = 45 |
|---|
| 11 | 37Na | |
| 12 | 38Mg | |
| 13 | 39Al | |
| 14 | 40Si | |
| 15 | 41P | 45P |
| 16 | 42S | 45S |
| 17 | 43Cl | 45Cl |
| 18 | 44Ar | 45Ar |
| 19 | 45K | 45K |
| 20 | 46Ca | 45Ca |
| 21 | 47Sc | 45Sc |
| 22 | 48Ti | 45Ti |
| 23 | 49V | 45V |
| 24 | 50Cr | 45Cr |
| 25 | 51Mn | 45Mn |
| 26 | 52Fe | 45Fe |
| 27 | 53Co | |
| 28 | 54Ni | |
| 29 | 55Cu | |
| 30 | 56Zn | |
External data and identifiers
Literature and References
[1] - H. Morinaga, G. Wolzak:
Potassium 45.
In: Physics Letters, 11, 2, (1964), DOI 10.1016/0031-9163(64)90649-3.
Last update: 2025-12-16
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