Radium is a radioactive element with the symbol Ra and atomic number 88. Discovered by Marie Curie and Pierre Curie in 1898, it is found in trace amounts in uranium and thorium ores. Radium glows in the dark due to its radioactivity and was historically used in luminous paints for watches and clocks. Due to its radioactive properties, radium can be harmful to health. Exposure can lead to serious conditions, including cancer. As a result, the use of radium in consumer products has been largely discontinued, and safety regulations are in place to manage its handling and disposal.