The discovery of the element radium is one of the most famous stories in the science world. It started with the discovery of pitchblende, which is an ore of uranium that is four or five times more radioactive than uranium itself. Pitchblende was discovered by Antione-Henri Baecquerel in 1896. In Paris, France in 1898 Marie and Pierre Curie were studying pitchblende separately, met, got married to each other, and still continued their work on pitchblende. After successfully removing uranium from pitchblende, they noticed that the remaining material was still very radioactive, so they concluded that another radioactive element had to be present. This new substance was very similar to barium, but because its chloride was slightly stranger it could be concentrated by fractional crystallization, which is a process used to separate components from a mixture through differences in physical or chemical properties. In 1902, after refining several tons of pitchblende from North Bohemia, one-tenth of a gram of radium chloride was produced.
Radium, Minnesota
Gammaspectrum of the shown Uranium ore with the ty...In 1911, Mme Curie and André-Louis Debierne isolated the element itself through the electrolysis of a pure radium chloride solution by using a mercury cathode and distilling it in an atmosphere of hydrogen gas. The decay products of radium were historically known as radium A, B, C, etc. Today we know that these are isotopes of different elements, shown in the chart to the right. Radium E became the first radioactive element to be made synthetically on February 4, 1936.
Radium naturally occurs from the breaking down of uranium and is therefore found in all uranium-bearing ores. Seven metric tons of pitchblende yields only one gram of radium. Today, the element is found in the carnotite (which is a hydrated potassium uranyl vanadate mineral) sands in Colorado, but richer ores are found in the Democratic Republic of the...