The Discovery of Francium

Early in the twentieth century, after viewing improved forms of the periodic table, people believed that there had to be an element below cesium. All who searched for it, though, were soon disappointed. Even the scientists who reported finding it were all proved to be mistaken. Finally, in 1939, Marguerite Perey at the Curie Institute in Paris discovered this element…francium. She had purified a sample of actinium free of all its radioactive decay products, but still observed that the sample had a beta ray emission which it was giving out more intense than it should have been. Because of this finding, she realized that there must be another element present, element 87, which was correct.

Using radiochemical techniques, it has been found that the most stable state of francium is in the ion Fr+. It is highly likely that its chemical characteristics would be very similar to the element above it’s, Cesium, as they are in the same group (alkali metals). If an oxide was ever made with francium, it would be Fr2O, although this has never been accomplished, yet. Of all the radioactive elements with atomic numbers 1 to 100, francium’s longest lived isotope is still the element with the shortest half-life, making it the most unstable of them all.

            Francium is highly radioactive and is found in minute amounts in uranium ore. There is only one francium atom per 1018 atoms of uranium, though. The quantities used for research are either produced in a nuclear reactor by bombarding radium with neutrons, or in a cyclotron by bombarding thorium with protons. Despite its ability to be made, francium’s longest lived atom only has a half-life of about 22 minutes, but most of the other isotopes have half-lives of less than1 minute. Because of this, no real use for it has been found and no weighable quantity of it has ever been made. Since francium has never been encountered outside a nuclear facility of a research laboratory, it has no useful purpose in living things. There is probably less than 30 grams of francium in the Earth’s crust at any one time.