October 31 - November 3, 2004
Element of the Day
Friday, October 15
The element was named for France. Francium is the least stable of the first 101 elements. It's longest lived isotope, 223Fr, has a half life of 22 minutes. The 223Fr isotope is produced by the alpha decay of actinium. In the earth's crust as a whole, at any given time there is probably only 25 - 30g of francium. This amount is, of course, distributed throughout the crust and represents the amount in equilibrium with its host ore. No weighable amounts of francium have ever been produced, nor are ever likely to be, due to its extreme transient nature.
Discovered by: Marquerite Perey in Paris, 1939.
Uses: In spite of its short life, francium has been applied in practice to the determination of actinium in natural objects. Formally, these determinations were carried out by measuring the activities of all the 227Ac decay products after three months, when equilibrium had been established. Francium is separated from actinium three hours after the latter has been isolated from natural products, and the ß- activity of 223Fr is measured. 223Fr has been used in limited biological research. In the study of the distribution of Fr, Rb and Cs in different organs of rats, it was found that the alkali metals accumulate chiefly in the kidneys, liver and salivary glands. It was shown that Fr is also fixed in an experimentally-induced sarcoma. Increase in the activity of Fr in the affected tissue appears immediately after onset of growth. This diagnostic method for cancerous diseases could be promising as there is no [little?] damage to the organism because of the short lifetime of either 223Fr or 212Fr.
Apart from these applications, there is no commercial application of Francium, due to its transient nature