The reaction between lithium and water
When lithium reacts with water, lithium hydroxide and hydrogen gas are produced. Lithium hydroxide is an alkali.
When lithium reacts with water it does not produce heat quickly enough to ignite the hydrogen given off or melt the lithium, which has a higher melting point than potassium and sodium.
The reaction between lithium and water in more detail
Note: You will not need to know this information but it may help to provide you with a better understanding of what happens in this reaction.