Do you know what alkali metals are?
Well, they are found in the first group (column) of the Periodic Table starting from Lithium. From top to the bottom are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). These are all metals and as you go down the group, the reactivity of these increase. Here's a nice video showing how the reactivity of alkali metals change down the group and to what extent.
Enjoy!
Caution!
Never mix Alkali metals with H2O
