Beryllium has 2 electrons in their outermost shell and has highly reactive than boron because Boron needs 3 electrons to lose whereas, beryllium needs to lose only 2 electrons to get stability. Silicon has 4 electrons in its outermost shell and is less reactive than aluminum because aluminum has to lose 3 electrons to get stability as compared to silicon which needs 4 electrons to lose to be stable and non-reactive.
