Question

What is the most reactive metal on the periodic table?

Answer 1

In theory it is francium (Fr), but experimentally it is cesium (Cs).

Explanation:

There is never enough francium with which to experiment because its isotopes have a very short half-life (the longest is about 22 min), and there is only about 20-30 grams in the earth's crust at any given time. http://education.jlab.org/itselemental/ele087.html

Cesium is present in large enough amounts to be studied, and experimentally it is the most reactive metal.

Reactions of the alkali metals in water.