Why is He over Ne in the periodic table?

Answer 1

The number of protons in the nucleus increases as you go to the right or go down in the Periodic Table. Elements of the same period exhibit common characteristics and are placed in the same column. In this case, both helium (He) and neon (Ne) are "noble gases", i.e. they have full electron shells and are extremely unreactive; noble gases do not even form diatomic molecules like some of their neighbors in the periodic chart like oxygen and chlorine.

The first electron shell to fill is the 1s shell, which fills with 2 electrons. Helium, with two protons in its nucleus is the first element to have a full shell. It thus sits at the top of the table. The next orbitals to fill are the 2s and 2p which require 2 and 6 electrons respectively. Neon, with 10 protons in its shell is the first element to fill both these shells and this sits immediately below helium in the table.