The First Dozen Energy Levels of Selected Neutral Atoms (eV below ionization)
level	element				comment
	hydrogen	helium	neon	sodium
∞	0	0	0	0	ionization
…	…	…	…	…
12	-0.094	-0.914	-2.861	-0.794
11	-0.112	-0.993	-2.872	-0.795
10	-0.136	-1.500	-2.928	-0.851
9	-0.167	-1.513	-2.952	-0.855
8	-0.212	-1.580	-2.989	-0.856
7	-0.277	-1.667	-3.010	-1.023
6	-0.377	-1.869	-3.183	-1.386
5	-0.543	-3.369	-4.717	-1.522
4	-0.849	-3.623	-4.850	-1.948
3	-1.510	-3.971	-4.894	-3.035
2	-3.399	-4.767	-4.946	-3.037
1	-13.598	-24.587	-21.565	-5.139	ground state
Source: NIST Atomic Spectra Database