# Do all single-electron species have the same orbital energies? [closed]

This picture from Ebbing's General Chemistry [1, p. 234] shows the electron orbital energies for a hydrogen atom, where each subshell belonging to the same principal quantum number ($$n = 1, 2, \cdots$$) are on the same level. Is this true for any particle with only one electron? Would, $$\ce{Li+}$$, for example, have the same orbital energies?

### References

1. Ebbing, D. D.; Gammon, S. D. General Chemistry, 11th ed.; Cengage Learning: Boston, MA, USA, 2017. ISBN 978-1-305-85914-2.
• Please always cite the source the illustration has been taken from. – andselisk Jan 7 at 8:52
• Since every distinct elementary nucleus has a different charge, why would you expect a single electron system based on that nucleus to have the sameenergy as a hydrogen atom which has only a single positive charge? – matt_black Jan 7 at 14:21
• @matt_black you're right. They will have different values of energy but the individual subshells will have same energy for a particular value of n for they are degenerate. – Priyanshu Das Jan 8 at 4:16

It would have to be $$\ce{Li^2+}$$ or $$\ce{He+}$$ to have 1 electron only.
For multielectron atoms/ions, energies of different orbitals with the same quantum number $$n$$ differ, due electron repulsion and kernel shielding. That is the reason why the orbital 4s is occupied before orbitals 3d.