Electron configuration
There are four kinds of electron configurations: s, p, d, and f orbitals. Each orbital can house a maximum of 2 electrons. S orbitals are roughly sphere-shaped, p orbitals are polar and shaped like a dumbbell, d orbitals are usually shaped like a four-leaf clover, and f orbitals form a mathematically complex shape. Orbitals can have different energy levels. For example 1s is a low energy sphere-shaped orbital while 3s is a higher energy sphere-shaped orbital. An atom can have more than one orbital; in fact, all except hydrogen do. Similarly, atoms can have more than one of each kind of orbital.