Thulium: properties of free atoms

Thulium atoms have 69 electrons and the shell structure is

The ground state electron configuration of ground state gaseous neutral thulium is  [Xe].4f13.6s2 and the term symbol is  2F7/2.

Atomic spectrum


A representation of the atomic spectrum of thulium.

Electronic configuration of neutral atomic thulium

Electronic configuration of thulium

The electronic configuration of thulium.

Kossel shell structure of thulium

The Kossel shell structure of thulium.

Ionisation Energies and electron affinity

The electron affinity of thulium is 50 kJ mol‑1. The ionisation energies of thulium are given below.

Ionisation energies of thulium
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 thulium
2s50.95 2p64.64  
3s47.92 3p48.48 3d55.37  
4s37.14 4p35.99 4d32.94 4f28.63
5s20.04 5p17.73 5d(no data)  
6s8.58 6p(no data)  


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 thulium. 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 1s59390 [1]
L I2s10116 [1]
L II2p1/29617 [1]
L III2p3/28648 [1]
M I3s2307 [1]
M II3p1/22090 [1]
M III3p3/21885 [1]
M IV3d3/21515 [1]
M V3d5/21468 [1]
N I4s470.9 [2]
N II4p1/2385.9 [2]
N III4p3/2332.6 [2]
N IV4d3/2175.5 [2]
N V4d5/2175.5 [2]
N VI4f5/2 -
N VII4f7/24.6 [1]
O I5s54.7 [2]
O II5p1/231.8 [2]
O III5p3/225 [2]


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.

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