Editing Period 3 element (section)

=== Sodium ===
{{Main|Sodium}}
''Sodium'' (symbol '''Na''') is a soft, silvery-white, highly reactive metal and is a member of the [[alkali metals]]; its only stable [[isotope]] is <sup>23</sup>Na. It is an abundant element that exists in numerous minerals such as [[feldspar]]s, [[sodalite]] and [[halite|rock salt]]. Many salts of sodium are highly soluble in water and are thus present in significant quantities in the Earth's bodies of water, most abundantly in the oceans as [[sodium chloride]].

Many sodium compounds are useful, such as sodium hydroxide (lye) for [[soap]]making, and sodium chloride for use as a deicing agent and a nutrient. The same [[ion]] is also a component of many minerals, such as [[sodium nitrate]].

The free metal, elemental sodium, does not occur in nature but must be prepared from sodium compounds. Elemental sodium was first isolated by [[Humphry Davy]] in 1807 by the [[electrolysis]] of [[sodium hydroxide]].