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All other potassium isotopes have half-lives under a day, most under a minute. The least stable is 31 K, a three-proton emitter discovered in 2019; its half-life was measured to be shorter than 10 picoseconds. [5] [6] Stable potassium isotopes have been used for several nutrient cycling studies since potassium is a macronutrient required for ...
A 70 kg human body contains about 140 g of potassium, hence about 140g × 0.0117% ≈ 16.4 mg of 40 K; [7] whose decay produces about 3850 [8] to 4300 disintegrations per second continuously throughout the life of an adult person (and proportionally less in young children). [Note 3] [9]
An example is calcium-40, with 20 neutrons and 20 protons, which is the heaviest stable isotope made of the same number of protons and neutrons. Both calcium-48 and nickel-48 are doubly magic because calcium-48 has 20 protons and 28 neutrons while nickel-48 has 28 protons and 20 neutrons. Calcium-48 is very neutron-rich for such a relatively ...
Except 20, 50 and 82 (all these three numbers are magic numbers), all other neutron numbers have at most 4 stable nuclides (in the case of 20, there are 5 stable nuclides 36 S, 37 Cl, 38 Ar, 39 K, and 40 Ca, and in the case for 50, there are 5 stable nuclides: 86 Kr, 88 Sr, 89 Y, 90 Zr, and 92 Mo, and 1 radioactive primordial nuclide, 87 Rb).
Conversely, of the 251 known stable nuclides, only five have both an odd number of protons and odd number of neutrons: hydrogen-2 , lithium-6, boron-10, nitrogen-14, and tantalum-180m. Also, only four naturally occurring, radioactive odd–odd nuclides have a half-life >10 9 years: potassium-40, vanadium-50, lanthanum-138, and lutetium-176.
The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger. This is a list of chemical elements by the stability of their isotopes. Of the first 82 elements in the periodic table, 80 have isotopes considered to be stable. [1] Overall, there are 251 known stable isotopes in ...
the sum of the rest mass of the individual nuclei = 6.015 + 2.014 = 8.029 u; the total rest mass on the two helium-nuclei = 2 × 4.0026 = 8.0052 u; missing rest mass = 8.029 – 8.0052 = 0.0238 atomic mass units. In a nuclear reaction, the total (relativistic) energy is conserved.
Neutral potassium atoms have 19 electrons, one more than the configuration of the noble gas argon. Because of its low first ionization energy of 418.8 kJ/mol, the potassium atom is much more likely to lose the last electron and acquire a positive charge, although negatively charged alkalide K − ions are not impossible. [23]