See also: List of individual Calcium isotopes (and general data sources).
General data
Name of the isotope:Calcium-40; Ca-40Symbol:40Ca or 4020CaMass number A:40 (= number of nucleons)Atomic number Z:20 (= number of protons)Neutrons N:20Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1 (= neutron-proton ratio)Neutron excess (N-Z):0Isotopic mass:39.9625909(2) u (atomic weight of Calcium-40)Nuclide mass:39.9516195 u (calculated nuclear mass without electrons)Mass excess:-34.84635 MeVMass defect:0.36720806 u (per nucleus)Nuclear binding energy:342.05210464 MeV (per nucleus) 8.55130262 MeV (average binding energy per nucleon)Separation energy:SN = 15.6350(6) MeV (first neutron) SP = 8.32816(2) MeV (first proton)Half-life:stableSpin and parity: (nuclear angular momentum)0+Charge radius:3.4776(19) femtometer fmYear of discovery:1922
Comparison of the natural Calcium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):
Atomic Mass ma
Quantity
Half-life
Spin
Calcium Isotopic mixture
40.078 u
100 %
Isotope 40Ca
39.9625909(2) u
96.941(156) %
stable
0+
Isotope 41Ca
40.96227792(15) u
[trace]
9.94(15) × 104 years
7/2-
Isotope 42Ca
41.958618(1) u
0.647(23) %
stable
0+
Isotope 44Ca
43.955482(2) u
2.086(110) %
stable
0+
Isotope 46Ca
45.95369(2) u
0.004(3) %
stable
0+
Isotope 48Ca
47.952522654(19) u
0.187(21) %
5.3 × 1019 years
0+
Isotope 43Ca
42.95876638(24) u
0.135(10) %
stable
7/2-
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 20) and isobaric (same nucleon number A = 40) with Calcium-40. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
