Calcium: 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.

Atomic spectrum

 

A representation of the atomic spectrum of calcium.

Electronic configuration of neutral atomic calcium

Electronic configuration of calcium

The electronic configuration of calcium.

Kossel shell structure of calcium

The Kossel shell structure 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
1st589.8
2nd1145.4
3rd4912.4
4th6491
5th8153
6th10496
7th12270
8th14206
9th18191
10th20385
11th57110
12th63410
13th70110
14th78890
15th86310
16th94000
17th104900
18th111710
19th494850
20th527760

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
1s19.47  
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.

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