The element whose name comes from the Latin for “ray” and was discovered by Marie Curie is radium. Marie and Pierre Curie announced radium in December 1898 after studying pitchblende, a uranium ore, and finding that its leftover material was even more radioactive than uranium itself.
The name reflects radium’s powerful emissions: it was formed from the Latin radius, meaning “ray.” The Curies identified radium compounds in the ore, but isolating the element was extraordinarily difficult because only tiny quantities were present. Marie Curie and André-Louis Debierne finally isolated metallic radium in 1910.
Radium is a radioactive alkaline-earth metal with the symbol Ra and atomic number 88. It is often confused with polonium, another element discovered by the Curies in 1898. Polonium was named after Marie Curie’s homeland, Poland, while radium refers to radiation. Radium’s decay can produce radon gas, a major part of its health hazard. The historical unit “curie” was originally based on the activity of radium-226.