Group IIA The Alkaline Earth Metals

As we noted in Section 22.1, a second-period element is often considerably different from the other elements in its column. Those differences become more pronounced as you progress to the right in the periodic table. We briefly noted differences in properties of lithium from those of the other alkali metals, though those differences are not great. Beryllium, however, shows rather marked differences from the other alkaline earth elements. We have already noted that beryUium differs in its lack of reactivity compared with the other Group IIA metals. Another notable diffoence is in the properties of the hydroxides. Whereas those of the elements magnesium to barium are basic, beryllium hydroxide is amphoteric, reacting with both acids and bases. 

Like the alkali metals, the Group IIA elements occur in nature as silicate rocks. They also occur as carbonates and sulfates, and many of these are commercial sources of alkaline earth metals and compounds. 

Magnesium metal turnings are in the beaker (left). Barium metal (right) is much more reactive than magnesium and must be stored in a bottle of kerosene to exclude moisture and oxygen, with which barium reacts. 

Magnesium metal is isolated from seawater by the Dow process, which is described in Section 13.2. 

Magnesium alloys are used in many motorcycle parts. Shown here is a closeup of the engine area of a Harley-Davidson motorcycle.TheV engine (upper right), engine block (lower right),and transmission case (lower left) are made of an aluminum-magnesium alloy. 

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