When reading the Periodic Table of the Elements most Families have the same # of "e" the 1st energy shell as..

Question

When reading the Periodic Table of the Elements most Families have the same number of electrons on the first and last shell. For example, Group II Period 2, they all have 2 electrons on the first shell and 2 electrons on the last energy shell. Can anyone explain why some elements do not follow this pattern? The Lanthanide and Actinide Series do not and some on the most common elements (Nb Niobium 2 and 1 while the rest of the Family has 1 and 1) do not follow this pattern. Please explain in simple terms! LOL

Answer 1

They are broken down by type of orbital the bottom two rows by the f orbital. Those had to be added after the s,p, and d orbitals of the upper chart. Most of those orbitals have specific shapes and energies, and the electrons can have several combinations to get the lowest energy level.