Calcium is a chemical element of the second group and the fourth period, with an atomic number of 20 and an atomic mass of 40.078. Calcium is called differently in different languages, but in Latin its name is Calcium. Calcium has many isotopes (from Ca-34 to Ca-58). Many of them are artificial radioactive with a half-life of less than 1 second. Calcium has 5 stable isotopes, the most abundant being Ca-40 (96% in abundance). Of the radioactive isotopes, Ca-48 is considered the longest-lived, wit