alkaline-earth metal n.
Any of a group of metallic elements including calcium, strontium, magnesium, barium, beryllium, and radium.
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.