Radium is a chemical element, having the chemical symbol Ra. Its atomic number (the number of protons) is 88. It has a standard atomic weight of 226 g•mol −1 and it is a solid in its elemental form.
Radium is considered a member of the "Alkali earth metal" class of elements. At a pressure of 101.325 kPa, it has a boiling point of 1,737 °C and a melting point of 700 °C.