Orbitals may contain only two electrons each. Electrons move around in orbitals, which are areas where electrons have a high possibility of being found. Orbitals are grouped together into energy levels.
Each energy level contains a specific number of orbitals. The first energy level of every atom contains only one orbital: the s orbital. With each subsequent energy level, more orbitals are added.
Each energy level can only have one s orbital, which is spherical in shape. The next orbitals added are the p orbitals, which look like dumbbells. Once the s orbitals fill up, the electrons spill over onto the p orbitals. The next orbitals are the d and the f.
An element can be represented by a figure depicting the electrons present in each orbital and energy level. Oxygen, atomic number 8, would have a configuration of 1s2 2s2 2p4; and iodine, with an atomic number of 53, would have 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5 as its configuration.