The alkali metals are located in Group 1 of the periodic table. Here's how to find the answer:

* Alkali Metals: These elements are highly reactive and have one electron in their outermost shell. They include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr).

* Mass Greater than 200: You need to find the alkali metal with an atomic mass higher than 200.

The answer is Francium (Fr). Francium has an atomic mass of approximately 223.