Name:
$(a)$ three elements that have a single electron in their outermost shells.
$(b)$ two elements that have two electrons in their outermost shells.
$(c)$ three elements with filled outermost shells.

(N/A) Lithium $(Li)$,sodium $(Na)$,and potassium $(K)$ have a single electron in their outermost shells.
$(b)$ Magnesium $(Mg)$ and calcium $(Ca)$ have two electrons in their outermost shells.
$(c)$ Neon $(Ne)$,argon $(Ar)$,and xenon $(Xe)$ have filled outermost shells.