You will find calcium in the second column of the period table with other elements including beryllium and magnesium. Those elements make up the alkali earth metal family. Yes, calcium is defined as a metal because of both its physical and chemical traits. They all have an outer shell with two electrons and are very reactive. Those elements in the second column have two electrons ready to make compounds. It shouldn’t surprise you that calcium has a valence of 2.

You won’t find calcium sitting around as a pure element. In nature, calcium is always found in compounds with other elements. One of the most famous compounds is limestone (CaCO₃).