From Na To The Very End

The next period of periodical table consists of 8 elements. It begins with Na and Mg having (3s)-shell being fulfilled then the 3p-shell is fulfilled in Al, Si, P, S, Cl elements and it is finally occupied by electrons in Ar. These elements have the same spectroscopic ground state terms as period Li, Be,...Ne and its chemical behaviors are similar. The ionization energies are slightly lower in this period (see chapter "Configuration of all elements").

It amazes a bit that the period is closed by Argone because the 3d-shell isn't fully occupied. However, the energy difference between 3p and 3d is quite big in order to be closer to 4s-electrons for 3d-electrons. The energy separation 4s - 3d is so small that there are competition between orbitals: 4s, 4s2, 4s23d, 4s23d2, 4s23d3, 4s3d5, 4s23d5, 4s23d6, 4s23d7, 4s23d8, 4s3d10, 4s23d10. Then the 4p-shell is fully occupied and the period is closed by Krypton (z = 36).

The last consequence from z = 19 to z = 36 with occupation of 4s, 3d and 4p orbitals repeats for elements beginning from number 37 till 54. Element series with occupation of 5s, 4d and 5p orbitals is ended by Xenon.

6s-shell is occupied in the two successive elements, Caesium and Barium, and the the new 5d-orbital occupation begins then from Lanthanum. However, beginning from the next element, Cerium, the new 4f-shell begins to be occupied. The 4f-shell is fully occupied in 71st element, Lutetium. The binding energy of 4f-electrons lies in the same region as that of 5d-electrons so that it's possible to meet small variations while binding.

Beginning from 72nd element the 5d-shell is occupied fully in Mercury. The 6p-orbital is closed in Ru (z = 86).

The next row is built in the same style like the previous one from Z = 55 till Z = 86 (Cs - Ru); so firstly 7s-orbital then 6d ↔ 5f in mixture. But unfortunately since nuclei begin to be more unstable and short-lived (sphere of nuclear physics knowledge) experimental values are no longer reliable for such heavy atoms. But we don't doubt the orbital construction principle for these atoms and will meet the next noble gas when Z = 118, that's for sure. The possible Configurations till Z = 112 are given on the below illustration.

The rough scheme of series of occupied energy states is given by a curve here.