Original sentence: Exceptions include lithium, sodium, potassium, and rubidium of the alkali metals; and [magnesium]], calcium, strontium, and barium of the alkaline earth metals; and europium and ytterbium of the rare earth metals
Edited sentence: Exceptions include lithium, sodium, potassium, and rubidium of the alkali metals; and magnesium, calcium, strontium, and barium of the alkaline earth metals; and europium and ytterbium of the rare earth metals