Alkali metals are known for their high reactivity, particularly with ______, resulting in the formation of hydroxides and the release of hydrogen gas.

Alkali metals are extremely reactive because they have one electron in their outer shell that they can lose easily. When they encounter water, that lone electron is transferred to a water molecule, breaking the H–O bonds. The metal ion then combines with hydroxide ions from the water, forming a metal hydroxide, while the hydrogen atoms from the water are released as hydrogen gas. For example, sodium metal reacts with water to give sodium hydroxide and hydrogen gas. This reaction demonstrates why alkali metals are handled with great care.