Here's a breakdown:

* Alkali Metals: These are the elements in Group 1 of the periodic table (Li, Na, K, Rb, Cs, Fr). They are highly reactive metals.

* Hydrogen: A highly reactive nonmetal.

* Metal Hydrides: Compounds formed by the reaction of an alkali metal with hydrogen.

Reaction:

2M + H₂ → 2MH (where M is an alkali metal)

Examples:

* Lithium hydride (LiH)

* Sodium hydride (NaH)

* Potassium hydride (KH)

Properties of Metal Hydrides:

* They are ionic compounds with a high melting point.

* They are strong reducing agents.

* They are often used in organic chemistry as bases.

Let me know if you'd like to know more about any of these topics!