A plot of Atomic Number (Z) versus Electron Binding Energies for the Elements with labels showing the energy vs Z pattern for the inner orbitals.
<a href="https://en.wikipedia.org/wiki/User:Bvcrist" class="extiw" title="en:User:Bvcrist">en:User:Bvcrist</a>
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English Wikipedia, <a href="https://en.wikipedia.org/wiki/File:BE_vs_Z.jpg" class="extiw" title="en:File:BE vs Z.jpg">en:File:BE vs Z.jpg</a>. The person who put this here didn't give the source of the data, but they correspond more or less to data given in Table 1-1 of the <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200922175049/http://www.physics.uwo.ca/~lgonchar/courses/p9826/xdb.pdf">X-RAY DATA BOOKLET</a> of the Lawrence Berkeley National Laboratory.