http://www.ck12.org Chapter 2. Matter
MEDIA
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URL: http://www.ck12.org/flx/render/embeddedobject/79980Reactivity of Alkaline Earth Metals
All alkaline Earth metals have similar properties because they all have two valence electrons. They readily give up
their two valence electrons to achieve a full outer energy level, which is the most stable arrangement of electrons. As
a result, they are very reactive, although not quite as reactive as the alkali metals in group 1. For example, alkaline
Earth metals will react with cold water, but not explosively as alkali metals do. Because of their reactivity, alkaline
Earth metals never exist as pure substances in nature. Instead, they are always found combined with other elements.
The reactivity of alkaline Earth metals increases from the top to the bottom of the group. That’s because the atoms
get bigger from the top to the bottom, so the valence electrons are farther from the nucleus. When valence electrons
are farther from the nucleus, they are attracted less strongly by the nucleus and more easily removed from the atom.
This makes the atom more reactive.
Q:Alkali metals have just one valence electron. Why are alkaline Earth metals less reactive than alkali metals?
A:It takes more energy to remove two valence electrons from an atom than one valence electron. This makes
alkaline Earth metals with their two valence electrons less reactive than alkali metals with their one valence electron.