Francium is a chemical element that has the symbol Fr and atomic
number 87. It has the lowest known electronegativity and is the second
rarest naturally occurring element on Earth (after astatine)<!-- Cf
and others occur naturally in supernovae; Universe-wide abundance is
difficult to ascertain -->. Francium is a highly radioactive metal
that decays into astatine, radium, and radon. As an alkali metal, it
has one valence electron. Marguerite Perey discovered francium in
1939. Francium was the last element discovered in nature, rather than
synthesized. Outside the laboratory, francium is extremely rare, with
trace amounts found in uranium and thorium ores, where the isotope
francium-223 is continually formed and continually decays. Perhaps an
ounce (30 g) exists at any given time throughout the Earth's crust;
the other isotopes are entirely synthetic. The largest amount ever
collected of any isotope was a cluster of 10,000 atoms (of
francium-210) created as an ultracold gas at Stony Brook in 1996.
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Today's selected anniversaries:
The Cutty Sark, one of the last sailing clippers ever to be built,
was launched at Dumbarton in Scotland.
The United Nations Security Council unanimously adopted Resolution
242 in the aftermath of the Six-Day War between Israel and Egypt,
Jordan, and Syria.
Two days after the death of Francisco Franco, Juan Carlos was
declared King of Spain according to the law of succession promulgated
Angela Merkel assumed office as the first female Chancellor of
Wiktionary's Word of the day:
extraneous: Not belonging to, or dependent upon, a thing; not
essential or intrinsic; foreign.
Wikiquote of the day:
This is life to come, — Which martyred men have made more glorious For
us who strive to follow. May I reach That purest heaven, — be to other
souls The cup of strength in some great agony, Enkindle generous
ardor, feed pure love, Beget the smiles that have no cruelty, Be the
sweet presence of a good diffused, And in diffusion ever more intense!
So shall I join the choir invisible Whose music is the gladness of the
world. -- George Eliot