Isotopes and The First Pictures of Francium

The first pictures ever taken of the rare element Francium were taken at the University of New York, Stony Brook.

Discovered in 1939 by Marguerite Perey, francium, the heaviest known member of the alkali metal series, occurs as a result of alpha decay of the element actinium. Also, it can be made by bombarding thorium with protons. While it occurs naturally in uranium mineral, there is probably less than an ounce of francium at any given time in the total crust of the Earth. It is the most unstable of the first 101 elements in the periodic table. 36 isotopes and isomers of francium are currently recognized. 223Francium is the longest lived isotope and the only isotope occurring naturally in nature. The atomic mass of its longest lived isotope is 223.0197 amu. Because all known isotopes of francium are highly unstable, knowledge of the chemical properties of the element comes from radiochemical techniques. No weighable quantity of francium has ever been produced. Francium’s chemical properties most closely resemble that of cesium’s.

In 1996, researchers at the University of New York, Stony Brook, reported that they had produced francium atoms by bombarding 18O atoms at a gold target heated to almost its melting point. Collisions between the gold and oxygen nuclei created atoms of 210francium. This team reported that they had generated about 1 million 210francium ions per second and held 1000 or more atoms at a time for about 20 seconds in a magnetic trap they had created before the atoms decayed or escaped. Enough francium was trapped so that a video camera could capture the light given off by the atoms as the fluoresced. A cluster of about 10,000 francium atoms appeared as a glowing sphere that was only about 1 millimeter in diameter. It is now thought that francium atoms may be able to serve as miniature laboratories for generating reactions between electrons and quarks. 

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