Uranium is a silvery metallic chemical element that has atomic number
92 in the actinide series of the periodic table. The heaviest
naturally occurring element, uranium is nearly twice as dense as lead
and weakly radioactive. It occurs naturally in low concentrations in
soil, rock and water, and is commercially extracted from
uranium-bearing minerals such as uraninite. In nature, uranium atoms
exist as uranium-238 (99.275%), uranium-235 (0.72%), and a very small
amount of uranium-234 (0.0058%). Uranium decays slowly by emitting an
alpha particle. The half-life of uranium-238 is about 4.5 billion
years and that of uranium-235 is 700 million years, making them useful
in dating the age of the earth. Along with thorium and plutonium, it
is one of the three fissile elements, meaning it can easily break
apart to become lighter elements. This property of uranium-235 and to
a lesser degree uranium-233 generates the heat needed to run nuclear
reactors and provides the explosive material for nuclear weapons. Both
uses rely on the ability of uranium to produce a sustained nuclear
chain reaction. Depleted uranium (uranium-238) is used in kinetic
energy penetrators and armor plating.
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Today's selected anniversaries:
The Song Dynasty in Imperial China ended with a Mongolian victory in
the Battle of Yamen.
The search for the mouth of the Mississippi River led by French
explorer Robert Cavelier de La Salle ended with a mutiny and his
murder in present-day Texas.
Pluto was photographed for the first time, 15 years before it was
eventually discovered by Clyde Tombaugh at the Lowell Observatory.
Ten days after Pancho Villa and his cross-border raiders attacked
Columbus, New Mexico, U.S. General John J. Pershing led a punitive
expedition into Mexico to pursue Villa.
Argentine forces led by Alfredo Astiz occupied South Georgia,
precipitating the Falklands War against the United Kingdom.
Wikiquote of the day:
All Faith is false, all Faith is true: Truth is the shattered mirror
strown In myriad bits; while each believes his little bit the whole to
own. -- Sir Richard Francis Burton