Classification as alkaline earth metal

Summary

Calcium is classified as an alkaline earth metal because it belongs to Group 2 of the periodic table. Like other Group 2 elements (especially strontium, barium, and radium), it has two valence electrons in the outer s-orbital, which are very easily lost in chemical reactions. As a result, calcium almost always forms a divalent (Ca2+) ion with a stable noble-gas electron configuration (argon). In its compounds, calcium is therefore typically found in ionic forms. The article also notes that while lighter Group 2 elements such as beryllium and magnesium are sometimes included, they differ significantly in physical and chemical behavior, which is why the traditional definition of “alkaline earth metal” often excludes them.

Key Points

• 1

  Calcium is a Group 2 element, so it is classified as an alkaline earth metal.

• 2

  Calcium has two easily lost valence electrons and therefore forms Ca2+ almost exclusively in compounds.

• 3

  Calcium’s compounds are usually ionic, reflecting the stability of the noble-gas electron configuration after losing two electrons.