French physicist · 1909–1975
Marguerite Perey
Marguerite Perey discovered francium in 1939, the last element to be found in nature rather than made in a laboratory.
How Francium was found
Perey joined Marie Curie’s Radium Institute as a lab assistant at 19 and became an expert in purifying actinium. Measuring its radiation, she found a small amount of beta activity that did not fit actinium or its known products.
She showed that about 1 per cent of actinium-227 atoms decay by emitting an alpha particle, producing element 87. She named it francium, after France. It is so unstable that there is probably less than 30 grams of it in the Earth’s crust at any moment.
Life and career
Born 1909 · Died 1975
Perey was born in Villemomble, near Paris. After the discovery she earned her doctorate and became professor of nuclear chemistry at the University of Strasbourg.
In 1962 she became the first woman elected to the French Academy of Sciences, as a corresponding member. She died of cancer, likely caused by years of radiation exposure.
Also known for
- First woman elected to the French Academy of Sciences
Discovered in the same era
Other elements identified within ten years of 1939.