For elements in the first three periods of the periodic table (hydrogen - argon), the orbitals can simply be filled up by increasing energy energy level. A difficulty arises when we come to potassium.

"They touch when the electron orbitals of one atom overlap enough with the electron orbitals of the other atom that physical or chemical effects start happening," Baird explained. "This is ...

So bismuth has partially filled orbitals and should behave as a paramagnet. However, its position in row six of the periodic table means bismuth also possesses some unusual heavy-atom properties.