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Calcium - 20Ca: properties of free atoms

Calcium atoms have 20 electrons and the shell structure is  2.8.8.2.

The ground state electron configuration of ground state gaseous neutral calcium is  [Ar].4s2 and the term symbol is  1S0.

Kossel shell structure of calcium
Schematic electronic configuration of calcium.
Kossel shell structure of calcium
The Kossel shell structure of calcium.

Atomic spectrum

 

A representation of the atomic spectrum of calcium.

Ionisation Energies and electron affinity

The electron affinity of calcium is 2.37 kJ mol‑1. The ionisation energies of calcium are given below.

Ionisation energies of calcium
Ionisation energy number Enthalpy / kJ mol‑1
1st589.83
2nd1145.45
3rd4912.37
4th6490.9
5th8140
6th10500
7th12270
8th14210
9th18190
10th20380
11th57080
12th63510 (inferred)
13th70300
14th78850
15th86260
16th93950
17th105000
18th111704
19th494859
20th527761
Ionisation energies of calcium
Ionisation energies of calcium.

Effective Nuclear Charges

The following are "Clementi-Raimondi" effective nuclear charges, Zeff. Follow the hyperlinks for more details and for graphs in various formats.

Effective nuclear charges for calcium
1s19.4730  
2s13.78 2p16.04  
3s9.60 3p8.66 3d(no data)  
4s4.40 4p(no data) 4d(no data) 4f(no data)
5s(no data) 5p(no data) 5d(no data)  
6s(no data) 6p(no data)  
7s   

References

These effective nuclear charges, Zeff, are adapted from the following references:

  1. E. Clementi and D.L.Raimondi, J. Chem. Phys. 1963, 38, 2686.
  2. E. Clementi, D.L.Raimondi, and W.P. Reinhardt, J. Chem. Phys. 1967, 47, 1300.

Electron binding energies

Electron binding energies for calcium. All values of electron binding energies are given in eV. The binding energies are quoted relative to the vacuum level for rare gases and H2, N2, O2, F2, and Cl2 molecules; relative to the Fermi level for metals; and relative to the top of the valence band for semiconductors.
Label Orbital eV [literature reference]
K 1s4038.5 [2]
L I2s438.4 [3]
L II2p1/2349.7 [3]
L III2p3/2346.2 [3]
M I3s44.3 [3]
M II3p1/225.4 [3]
M III3p3/225.4 [3]

Notes

I am grateful to Gwyn Williams (Jefferson Laboratory, Virginia, USA) who provided the electron binding energy data. The data are adapted from references 1-3. They are tabulated elsewhere on the WWW (reference 4) and in paper form (reference 5).

References

  1. J. A. Bearden and A. F. Burr, "Reevaluation of X-Ray Atomic Energy Levels," Rev. Mod. Phys., 1967, 39, 125.
  2. M. Cardona and L. Ley, Eds., Photoemission in Solids I: General Principles (Springer-Verlag, Berlin) with additional corrections, 1978.
  3. Gwyn Williams WWW table of values
  4. D.R. Lide, (Ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 81st edition, 2000.
  5. J. C. Fuggle and N. Mårtensson, "Core-Level Binding Energies in Metals," J. Electron Spectrosc. Relat. Phenom., 1980, 21, 275.