Here's why:
* Alkali Metals: These elements belong to Group 1 of the periodic table. They are highly reactive due to having only one electron in their outermost shell, which they readily lose to form a +1 ion.
* Reactivity Trend: Reactivity increases as you go down the group. This is because the outermost electron is further from the nucleus, making it easier to remove.
* Atomic Size: Potassium has the largest atomic radius among the three, meaning its outermost electron is furthest from the nucleus and easiest to remove.
Therefore, potassium is the most reactive of the three.
