alkaline-earth metal

noun Chemistry.

1. any of the group of bivalent metals including barium, radium, strontium, calcium, and, usually, magnesium, the hydroxides of which are alkalis but less soluble than those of the alkali metals.

n.

1. Any of a group of metallic elements including calcium, strontium, magnesium, barium, beryllium, and radium.

1. Any of a group of metallic elements that includes beryllium, magnesium, calcium, strontium, barium, and radium. Because the alkaline-earth metals have two electrons in their outer shell, they react easily with other elements and are found in nature only in compounds. See Periodic Table.