Question

which is the most reactive element of group 1 and why?​

Answer 1

potassium is the most reactive metal because as we move from upward to downward direction the metals are hard to looose electron

Answer 2

Cesium is most reactive element. We all know that reactivity increases down the group . Due to that francium is looking more reactive . But it is not francium have too heavy nucleii than cesium and couse radioactivity . Due to that too heavy nuclii the intractions of nucleus is more to the electron and hence required high energy to remove it from the outermost shell than cesium . Their is no relation of radioactivity and tendency to foming compounds . Down to the francium the reactivity must be slightly decrease due to the heavy nuclei. So cesium is the most reactive element in group 1 and whole the perodic table.