Chemical Element: uranium

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Chemical-Element Information

Symbol: U
Atomic number: 92
Year discovered: 1789

Discovered by: Martin Heinrich Klaproth (1743-1817), a German chemist.

• A yellow glass containing more than one percent uranium oxide, dating back to 79 A.D., was found near Naples in Italy.
• During the first 150 years uranium was known, few uses could be found for it, and it was studied chiefly because it was the heaviest element then known.
• In 1938, Otto Hahn and Fritz Strassmann discovered that the uranium nucleus undergoes fission when bombarded with neutrons, and thus offered the possibility of giving up its nuclear energy in a sustained chain reaction.
• Klaproth recognized an unknown element in pitchblende from Saxony and attempted to isolate the metal in 1789.
• To this new substance, Klaproth gave the name uranium in honor of Sir William Herschel’s discovery of the planet Uranus in 1781.
• Uranium metal itself was first isolated, in 1841, by Eugène Melchoir Peligot, who reduced the anhydrous chloride with potassium.
• The radioactive nature of uranium was not appreciated for another 55 years when, in 1896, Henri Becquerel detected its radioactivity.
• The first self-sustaining nuclear chain reaction was conducted by Enrico Fermi at the University of Chicago on December 2, 1942.
• With the development of methods for controlling the rate of fission, the first wartime and peacetime applications of nuclear energy soon followed.
• The first atomic bomb test was detonated on July 16, 1945; and the first bomb used in warfare was dropped August 6, 1945.
• Atomic power for propulsion was used for the first time in a submarine (USS “Nautilus”) in 1956, and one of the first full-scale nuclear power electrical generators began production at Shippingport, Pennsylvania, on December 2, 1957.
• On March 28, 1979, America’s worst civilian nuclear power plant accident occurred.
• It was on this day that a cooling system failure caused a near-meltdown at the Three Mile Island plant in Pennsylvania.
• The accident so scared the American public that nuclear power went into an eclipse from which it has not recovered.
• It is said that nuclear power itself wasn’t the problem.
• The public lost confidence in the ability of power companies to manage their technology.

Name in other languages:

French: uranium

German: Uran

Italian: uranio

Spanish: uranio

Information about other elements may be seen at this Chemical Elements List.

A special unit about words that include chemo-, chem- may be seen here.