The alkaline earth metals are another name for the group 2 metals in the periodic table. They consist of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Although helium does sit in group 2 electronically, it is not considered an alkaline earth metal. The one thing all these metals have in common is that they have 2 electrons in their outermost s orbital that are easily lost to form 2+ cations (or ions with a double positive charge). As a result, they tend to form ionic bonds with anions, or negatively charged ions. With a single charged anion like chloride (Cl-), two anions would ionically bond to a single cation (CaCl2, for example). With doubly charged anions (liike oxygen), one anion would pair with one cation (CaO, for example).