Question

Of the four elements surrounding strontium in the periodic table, which is the most reactive? Of the four elements surrounding strontium in the periodic table, which is the most reactive? @Chemistry

Answer 1

Well, that's not an entirely unambiguous question. Reactive how? But, generally the Group 1A and 2A metals react by losing an electron and forming a +1 or +2 cation, respectively. So then the question becomes: which of those four elements loses an electron easiest? And the answer will be the element that is farthest left and farthest down in the Periodic Table, because the ability of an atom to hold onto its valence electrons decreases in that direction.

The only remaining problem is to understand what you mean by the "four elements surrounding strontium." When I consider which elements "surround" strontium, I find EIGHT: K, Ca and Sc in the Period above Sr, Rb to the left of Sr in the same Period and Y to the right, and then Cs, Ba and La in the Period below Sr.

Of those EIGHT the one the furthest left and down is cesium (Cs), and therefore Cs would be the answer -- the metal that most easily loses its one valence electron.