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Potassium-40 (40 K) is a radioactive isotope of potassium which has a long half-life of 1.25 billion years. It makes up about 0.012% (120 ppm) of the total amount of potassium found in nature. Potassium-40 undergoes three types of radioactive decay.
Potassium-40 - symbol 40 K - is a naturally occurring, primordial, radioactive isotope of the chemical element potassium with a half-life of 1.25 billion years; Earth's potassium consists of about 0.0117% (117 ppm) of this isotope, which is responsible for the weak natural radioactivity of the alkali metal.
40 K has the longest known half-life for any positron-emitter nuclide. The long half-life of this primordial radioisotope is caused by a highly spin-forbidden transition: 40 K has a nuclear spin of 4, while both of its decay daughters are even–even isotopes with spins of 0. 40
A person with a body mass of 70 kg contains about 0.0164 grams of the radioactive isotope 40 K; this results in a rate of about 4300 radioactive decays per second, to which a person is continuously exposed. The two following tables list the most important data and properties of the Potassium isotopes.
24 sie 2022 · Potassium-40 (40K) is a radioactive isotope of potassium which has a long half-life of 1.25 billion years. It makes up about 0.012% (120 ppm) of the total amount of potassium found in nature.
Click any isotope in diagram to see its data. Detailed decay information for the isotope potassium-40 including decay chains and daughter products.
Isotope Relative Atomic Mass Isotopic Composition Standard Atomic Weight Notes ; 19 : K : 39 : 38.963 706 4864(49) 0.932 581(44) 39.0983(1) 40 : 39.963 998 166(60)
