Potassium: isotope data

Although Potassium only has two stable isotopes (K-39 and K-41), the long-lived radioisotope K-40 is often also regarded as a stable isotope. Potassium isotopes, mainly K-40 and K-41, are used to study the impact of potassium on the growth of plants and of the human cardiovascular system.

Naturally occurring isotopes

This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of potassium are listed (including any which occur naturally) below.
39K 38.9637074 (12) 93.2581 (44) 3/2 0.3914658
40K 39.9639992 (12) 0.0117 (1) 4 -1.298099
41K 40.9618254 (12) 6.7302 (44) 3/2 0.2148699


Radiosotope data

Further data for naturally occuring isotopes of potassium are listed above. This table gives information about some radiosotopes of potassium, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
37K 36.9733769 EC to 37Ar 3/2 0.2032
38K 37.969080 7.63 m EC to 38Ar 3 1.37
40K 39.9639987 1.277 x 109 y EC to 40Ar 4
42K 41.9624031 12.36 h β- to 42Ca 2 -1.1425
43K 42.96072 22.3 h β- to 43Ca 3/2 0.163
44K 43.96156 22.1 m β- to 44Ca 2 -0.856
45K 44.96070 17.8 m β- to 45Ca 3/2 0.1734
46K 45.96168 1.8 m β- to 46Ca 2 -1.05
47K 46.96551 17.5 s β- to 47Ca 1/2 1.93
48K 47.96551 6.8 s β- to 48Ca; β- + n to 47Ca 2
49K 48.96745 1.26 s β- to 49Ca; β- + n to 48Ca

Sheffield ChemPuter isotope pattern calculator


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NMR Properties of potassium

Common reference compound: KI/D2O, 0.1 M.

Table of NMR-active nucleus propeties of potassium
  Isotope 1 Isotope 2 Isotope 3
Isotope 39K 40K 41K
Natural abundance /% 93.2581 0.0117 6.7302
Spin (I) 3/2 4 3/2
Frequency relative to 1H = 100 (MHz) 4.666373 5.802018 2.561305
Receptivity, DP, relative to 1H = 1.00 0.000476 0.000000612 0.00000568
Receptivity, DC, relative to 13C = 1.00 2.79 0.00359 0.0333
Magnetogyric ratio, γ (107 rad T‑1 s-1) 1.2500608 -1.5542854 0.68606808
Magnetic moment, μ (μN) 0.50543376 -1.4513203 0.27739609
Nuclear quadrupole moment, Q/millibarn 58.5 -73 71.1
Line width factor, 1056 l (m4) 46 5.2 67



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