Potassium-33
Properties and data of the isotope 33K.
Potassium-33 is a radioisotope of the chemical element potassium that has not yet been confirmed or experimentally observed.
Besides the element-specific 19 protons, it has 14 neutrons in its atomic nucleus; the sum of these nuclear constituents results in a mass number of 33.
See also: List of individual Potassium isotopes (and general data sources).
General data
Name of the isotope:Potassium-33; K-33Symbol:33K or 3319KMass number A:33 (= number of nucleons)Atomic number Z:19 (= number of protons)Neutrons N:14Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):0.73684210526316 (= neutron-proton ratio)Neutron excess (N-Z):-5Isotopic mass:33.00810(22) u (atomic weight of Potassium-33)Nuclide mass:32.9976772 u (calculated nuclear mass without electrons)Mass excess:7.5451 MeVMass defect:0.261884432 u (per nucleus)Nuclear binding energy:243.9437771 MeV (per nucleus)
7.39223567 MeV (average binding energy per nucleon)Separation energy:SN = 22.521(447) MeV (first neutron)Half-life:< 25 nsDecay constant λ:27725887.222398 s-1Specific activity α:5.059672676363 × 10+29 Bq g-1
1.367479101719 × 10+19 Ci g-1Spin and parity:
(nuclear angular momentum)(3/2+)Mirror nucleus:Silicon-33
Radioactive Decay
Half-life T½ = < 25 ns respectively 2.5 × 10-8 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
|---|
| p | 32Ar | ? | | |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 14) and isobaric (same nucleon number A = 33) with Potassium-33. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 14 | Isobar A = 33 |
| 5 | 19B | |
| 6 | 20C | |
| 7 | 21N | |
| 8 | 22O | |
| 9 | 23F | |
| 10 | 24Ne | 33Ne |
| 11 | 25Na | 33Na |
| 12 | 26Mg | 33Mg |
| 13 | 27Al | 33Al |
| 14 | 28Si | 33Si |
| 15 | 29P | 33P |
| 16 | 30S | 33S |
| 17 | 31Cl | 33Cl |
| 18 | 32Ar | 33Ar |
| 19 | 33K | 33K |
| 20 | 34Ca | |
External data and identifiers
Last update: 2026-01-07
Perma link: https://www.chemlin.org/isotope/potassium-33
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