Question

Which is more reactive between Na and K, give reasons

Answer 1

K is more reactive.....as according to the periodic table towards the left the metallic character increases down a group as the electropositivity increases down a group....so K being below Na is more reactive....

Answer 2

K has one more full shell of electron between the nucleus on the outermost electron .thus in K the outermost electron is better shielded from the attractive force of the nucleus it follows therefore that this outermost electron is more easily lost than it is in Na .so K can form K+ more readily than Na can form Na+