Potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

() has 25 known

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s from to as well as , as well as an unconfirmed report of . Three of those isotopes occur naturally: the two stable forms (93.3%) and (6.7%), and a very long-lived radioisotope Potassium-40, (0.012%) Naturally occurring radioactive decays with a half-life of 1.248×10⁹ years. 89% of those decays are to stable Calcium-40, by beta decay, whilst 11% are to Argon-40, by either electron capture or positron emission. This latter decay branch has produced an isotopic abundance of argon on Earth which differs greatly from that seen in gas giants and stellar spectra. has the longest known half-life for any positron-emitter nuclide. The long half-life of this primordial radioisotope is caused by a highly selection rule, spin-forbidden transition: has a nuclear spin of 4, while both of its decay daughters are even and odd atomic nuclei, even–even isotopes with spins of 0. occurs in natural potassium in sufficient quantity that large bags of potassium chloride commercial salt substitutes can be used as a radioactive source for classroom demonstrations. is the largest source of natural radioactivity in healthy animals and humans, greater even than carbon-14, . In a human body of 70 kg mass, about 4,400 nuclei of decay per second. The decay of to is used in potassium-argon dating of rocks. Minerals are dated by measurement of the concentration of potassium and the amount of radiogenic that has accumulated. Typically, the method assumes that the rocks contained no argon at the time of formation and all subsequent radiogenic argon (i.e., ) was retained. has also been extensively used as a radioactive tracer in studies of weathering. All other potassium isotopes have half-lives under a day, most under a minute. The least stable is , a three-proton emission, proton emitter discovered in 2019; its half-life was measured to be shorter than 10 picoseconds. Stable potassium isotopes have been used for several nutrient cycling studies since potassium is a macronutrient (ecology), macronutrient required for life.

List of isotopes

, -id=Potassium-31 , , style="text-align:right" , 19 , style="text-align:right" , 12 , 31.03678(32)# , <10 ps , 3p , ²⁸S , 3/2+# , , , -id=Potassium-34 , ³⁴K , style="text-align:right" , 19 , style="text-align:right" , 15 , 33.998404(18) , , p , ³³Ar , , , , -id=Potassium-35 , rowspan=2, ³⁵K , rowspan=2 style="text-align:right" , 19 , rowspan=2 style="text-align:right" , 16 , rowspan=2, 34.98800541(55) , rowspan=2, 175.2(19) ms , beta decay, β⁺ (99.63%) , ³⁵Ar , rowspan=2, 3/2+ , rowspan=2, , rowspan=2, , - , β⁺, p (0.37%) , ³⁴Cl , -id=Potassium-36 , rowspan=3, ³⁶K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 17 , rowspan=3, 35.98130189(35) , rowspan=3, 341(3) ms , β⁺ (99.95%) , ³⁶Ar , rowspan=3, 2+ , rowspan=3, , rowspan=3, , - , β⁺, p (0.048%) , ³⁵Cl , - , β⁺, alpha decay, α (0.0034%) , ³²S , -id=Potassium-37 , ³⁷K , style="text-align:right" , 19 , style="text-align:right" , 18 , 36.97337589(10) , 1.23651(94) s , β⁺ , ³⁷Ar , 3/2+ , , , -id=Potassium-38 , ³⁸K , style="text-align:right" , 19 , style="text-align:right" , 19 , 37.96908111(21) , 7.651(19) min , β⁺ , ³⁸Ar , 3+ , , , -id=Potassium-38m1 , rowspan=2 style="text-indent:1em" , ^38m1K , rowspan=2 colspan="3" style="text-indent:2em" , 130.15(4) keV , rowspan=2, 924.35(12) ms , β⁺ (99.97%) , ³⁸Ar , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , Isomeric transition, IT (0.0330%) , ³⁸K , -id=Potassium-38m2 , style="text-indent:1em" , ^38m2K , colspan="3" style="text-indent:2em" , 3458.10(17) keV , 21.95(11) μs , IT , ³⁸K , (7)+ , , , -id=Potassium-39 , ³⁹K , style="text-align:right" , 19 , style="text-align:right" , 20 , 38.9637064848(49) , colspan=3 align=center, Stable , 3/2+ , 0.932581(44) , , - , rowspan=3, potassium-40, ⁴⁰KUsed in potassium-argon datingPrimordial nuclide, Primordial radionuclide , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 21 , rowspan=3, 39.963998165(60) , rowspan=3, 1.248(3)×10⁹ y , β⁻ (89.28%) , ⁴⁰Ca , rowspan=3, 4− , rowspan=3, 1.17(1)×10⁻⁴ , rowspan=3, , - , Electron capture, EC (10.72%) , rowspan=2, ⁴⁰Ar , - , - , β⁺ (0.001%) , -id=Potassium-40m , style="text-indent:1em" , ^40mK , colspan="3" style="text-indent:2em" , 1643.638(11) keV , 336(12) ns , IT , ''⁴⁰K'' , 0+ , , , -id=Potassium-41 , ⁴¹K , style="text-align:right" , 19 , style="text-align:right" , 22 , 40.9618252561(40) , colspan=3 align=center, Stable , 3/2+ , 0.067302(44) , , -id=Potassium-42 , ⁴²K , style="text-align:right" , 19 , style="text-align:right" , 23 , 41.96240231(11) , 12.355(7) h , β⁻ , ⁴²Ca , 2− , TraceDecay product of ⁴²Ar , , -id=Potassium-43 , ⁴³K , style="text-align:right" , 19 , style="text-align:right" , 24 , 42.96073470(44) , 22.3(1) h , β⁻ , ⁴³Ca , 3/2+ , , , -id=Potassium-43m , style="text-indent:1em" , ^43mK , colspan=3 style="text-indent:2em" , 738.30(6) keV , 200(5) ns , IT , ⁴³K , 7/2− , , , -id=Potassium-44 , ⁴⁴K , style="text-align:right" , 19 , style="text-align:right" , 25 , 43.96158698(45) , 22.13(19) min , β⁻ , ⁴⁴Ca , 2− , , , -id=Potassium-45 , ⁴⁵K , style="text-align:right" , 19 , style="text-align:right" , 26 , 44.96069149(56) , 17.8(6) min , β⁻ , ⁴⁵Ca , 3/2+ , , , -id=Potassium-46 , ⁴⁶K , style="text-align:right" , 19 , style="text-align:right" , 27 , 45.96198158(78) , 96.30(8) s , β⁻ , ⁴⁶Ca , 2− , , , -id=Potassium-47 , ⁴⁷K , style="text-align:right" , 19 , style="text-align:right" , 28 , 46.9616616(15) , 17.38(3) s , β⁻ , ⁴⁷Ca , 1/2+ , , , -id=Potassium-48 , rowspan=2, ⁴⁸K , rowspan=2 style="text-align:right" , 19 , rowspan=2 style="text-align:right" , 29 , rowspan=2, 47.96534118(83) , rowspan=2, 6.83(14) s , β⁻ (98.86%) , ''⁴⁸Ca'' , rowspan=2, 1− , rowspan=2, , rowspan=2, , - , β⁻, neutron emission, n (1.14%) , ⁴⁷Ca , -id=Potassium-49 , rowspan=2, ⁴⁹K , rowspan=2 style="text-align:right" , 19 , rowspan=2 style="text-align:right" , 30 , rowspan=2, 48.96821075(86) , rowspan=2, 1.26(5) s , β⁻, n (86%) , ''⁴⁸Ca'' , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , β⁻ (14%) , ⁴⁹Ca , -id=Potassium-50 , rowspan=3, ⁵⁰K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 31 , rowspan=3, 49.9723800(83) , rowspan=3, 472(4) ms , β⁻ (71.4%) , ⁵⁰Ca , rowspan=3, 0− , rowspan=3, , rowspan=3, , - , β⁻, n (28.6%) , ⁴⁹Ca , - , β⁻, 2n? , ''⁴⁸Ca'' , -id=Potassium-50m , style="text-indent:1em" , ^50mK , colspan=3 style="text-indent:2em" , 172.0(4) keV , 125(40) ns , IT , ⁵⁰K , (2−) , , , -id=Potassium-51 , rowspan=3, ⁵¹K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 32 , rowspan=3, 50.975828(14) , rowspan=3, 365(5) ms , β⁻, n (65%) , ⁵⁰Ca , rowspan=3, 3/2+ , rowspan=3, , rowspan=3, , - , β⁻ (35%) , ⁵¹Ca , - , β⁻, 2n? , ⁴⁹Ca , -id=Potassium-52 , rowspan=3, ⁵²K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 33 , rowspan=3, 51.981602(36) , rowspan=3, 110(4) ms , β⁻, n (72.2%) , ⁵¹Ca , rowspan=3, 2−# , rowspan=3, , rowspan=3, , - , β⁻ (25.5%) , ⁵²Ca , - , β⁻, 2n (2.3%) , ⁵⁰Ca , -id=Potassium-53 , rowspan=3, ⁵³K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 34 , rowspan=3, 52.98680(12) , rowspan=3, 30(5) ms , β⁻, n (64%) , ⁵²Ca , rowspan=3, 3/2+ , rowspan=3, , rowspan=3, , - , β⁻ (26%) , ⁵³Ca , - , β⁻, 2n (10%) , ⁵¹Ca , -id=Potassium-54 , rowspan=3, ⁵⁴K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 35 , rowspan=3, 53.99447(43)# , rowspan=3, 10(5) ms , β⁻ , ⁵⁴Ca , rowspan=3, 2−# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁵³Ca , - , β⁻, 2n? , ⁵²Ca , -id=Potassium-55 , rowspan=3, ⁵⁵K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 36 , rowspan=3, 55.00051(54)# , rowspan=3, 10# ms
[>620 ns] , β⁻? , ⁵⁵Ca , rowspan=3, 3/2+# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁵⁴Ca , - , β⁻, 2n? , ⁵³Ca , -id=Potassium-56 , rowspan=3, ⁵⁶K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 37 , rowspan=3, 56.00857(64)# , rowspan=3, 5# ms
[>620 ns] , β⁻? , ⁵⁶Ca , rowspan=3, 2−# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁵⁵Ca , - , β⁻, 2n? , ⁵⁴Ca , -id=Potassium-57 , rowspan=3, ⁵⁷K , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 38 , rowspan=3, 57.01517(64)# , rowspan=3, 2# ms
[>400 ns] , β⁻? , ⁵⁷Ca , rowspan=3, 3/2+# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁵⁶Ca , - , β⁻, 2n? , ⁵⁵Ca , -id=Potassium-59 , rowspan=3, ⁵⁹KDiscovery of this isotope is unconfirmed. , rowspan=3 style="text-align:right" , 19 , rowspan=3 style="text-align:right" , 40 , rowspan=3, 59.03086(86)# , rowspan=3, 1# ms
[>400 ns] , β⁻? , ⁵⁹Ca , rowspan=3, 3/2+# , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁵⁸Ca , - , β⁻, 2n? , ⁵⁷Ca

References

{{Navbox element isotopes Isotopes of potassium, Potassium Lists of isotopes by element, Potassium

List of isotopes

See also

References