In what year did the Curies discover radium?

The Curies discovered radium in 1898. Marie and Pierre Curie reached this conclusion while studying pitchblende, a uranium ore mined near Jáchymov. They noticed that residues left after uranium extraction were more radioactive than uranium itself, suggesting that the ore contained an unknown element.

In July 1898, the Curies announced the discovery of polonium, named after Marie's native Poland. Later that year, they identified another new element in the same material. They announced radium to the French Academy of Sciences on 26 December 1898 and named it from the Latin radius, meaning “ray,” because of its powerful emissions.

The 1898 discovery refers to identifying radium compounds, not producing pure metallic radium. Marie Curie and André-Louis Debierne isolated radium metal only in 1910, using electrolysis of radium chloride. This distinction sometimes causes confusion when the discovery and isolation dates are treated as the same event. Radium-226 has a half-life of about 1,600 years and was later used in luminous paint and early medical treatments before its serious hazards became clear.