The chemical element of atomic number 88, a rare radioactive metal of the alkaline earth series. It was formerly used as a source of radiation for radiotherapy. (Symbol: Ra)
More example sentences
- Rutherford was studying the structure of matter by bombarding a very thin gold foil with the alpha radiation from radium and polonium.
- All isotopes of radium are radioactive with radium - 226 being the most stable.
- The ability of radioactive substances such as radium to radiate energy, apparently spontaneously and continuously, appeared to contradict the law of the conservation of energy.
late 19th century: from Latin radius 'ray' + -ium.
Definition of radium in:
- The British & World English dictionary