Thallium: properties of free atoms

Thallium atoms have 81 electrons and the shell structure is

The ground state electron configuration of ground state gaseous neutral thallium is  [Xe].4f14.5d10.6s2.6p1 and the term symbol is  2P1/2.

Atomic spectrum


A representation of the atomic spectrum of thallium.

Electronic configuration of neutral atomic thallium

Electronic configuration of thallium

The electronic configuration of thallium.

Kossel shell structure of thallium

The Kossel shell structure of thallium.

Ionisation Energies and electron affinity

The electron affinity of thallium is 19.2 kJ mol‑1. The ionisation energies of thallium are given below.

Ionisation energies of thallium
Ionisation energy number Enthalpy / kJ mol‑1

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 thallium
2s59.68 2p76.49  
3s57.42 3p58.37 3d67.53  
4s46.08 4p45.22 4d43.39 4f42.87
5s29.12 5p27.09 5d22.03  
6s12.82 6p12.25  


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 thallium. 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 1s85530 [1]
L I2s15347 [1]
L II2p1/214698 [1]
L III2p3/212658 [1]
M I3s3704 [1]
M II3p1/23416 [1]
M III3p3/22957 [1]
M IV3d3/22485 [1]
M V3d5/22389 [1]
N I4s846.2 [3]
N II4p1/2720.5 [3]
N III4p3/2609.5 [3]
N IV4d3/2405.7 [3]
N V4d5/2385 [3]
N VI4f5/2122.2 [3]
N VII4f7/2117.8 [3]
O I5s136 [2, values derived from reference 1]
O II5p1/294.6 [3]
O III5p3/273.5 [3]
O IV5d3/214.7 [3]
O V5d5/212.5 [3]


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).


  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.

WebElements Shop

You can buy periodic table posters, mugs, T-shirts, fridge magnets, games, molecular models, and more at the WebElements shop