Francium is the last of the known alkali metals and does not occur to any significant extent in nature. All known isotopes are radioactive and have short half-lives (22 minutes is the longest). The existence of Francium was predicted by Dmitri Mendeleev in the 1870's and he presumed it would have chemical and physical properties similar to cesium. That may well be, but not enough francium has been isolated to test. Numerous historical claims to the discovery of element 87 were made resulting in the names russium, virginium, and moldavium. However, the confirmed discovery is credited to Marguerite Perey who was an assistant to Marie Curie at the Radium Institute in Paris. She named the element after her native country.