The chemical symbol for calcium is "Ca." In the periodic table, it is classified as an alkaline earth metal and is found in group 2. Calcium has an atomic number of 20 and plays a vital role in biological systems, particularly in the functioning of bones and teeth in vertebrates. Beyond its importance in biology, calcium is also used in various industrial applications, including metal production, cement and concrete manufacturing, and as a reducing agent. Its reactive nature means that it easily forms compounds, most notably calcium carbonate, which is a common substance found in rocks and shells.