FACTS about Francium:
Francium does not have any stable isotopes. There is at most one ounce of francium in the whole earth at any given time as a result of the decay of other radioactive elements. It is the most unstable of the first 103 elements in the periodic table. Its longest lived isotope has a half life of 22 minutes.
Despite its radioactive complications, francium is the heaviest simple atom. It is an alkali and has many of the properties and is chemically similar to atoms in the same column of the periodic table: lithium, sodium potassium, rubidium and cesium. It has a low ionization energy so it readily gives up the outermost of its 87 electrons.
Since francium is now available about one week a month at Stony Brook, a whole series of measurements is possible. These include the location of energy levels and the lifetime of some of those levels. The ultimate goal of the project is the measurement of parity non-conservation in atomic francium. Much of the work done to date is in preparation for that measurement. It is necessary to understand the atomic structure very well and compare it to state of the art calculations.