see the periodic table of elements in the Reference Supplement
any of the six highly reactive
chemical elements in group IIA of the periodic table including, in order of increasing
reactivity, beryllium, magnesium, calcium, strontium, barium, and radium: an oxide
of any of these metals is called
an alkaline earth
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.