Each sublevel has differing numbers of orbitals. Sublevels are designated with lower-case letters. Sublevel s contains one orbital, p contains three, d has five, f has seven, g has nine, h has 11 and i has 13.

The periodic table of elements contains seven rows; therefore, elements can have up to seven energy levels, depending on how many electrons the element possess. Electrons travel around the atom in orbitals. Each orbital houses a maximum of two electrons.

With each subsequent energy level, another sublevel is added. Energy level one contains only one sublevel, the s with its one orbital. Energy level 2 contains s and p sublevels, so this energy level has a total of four orbitals. Energy level 3 has s, p and d sublevels; therefore, this energy level has a total of nine orbitals.