Discovery Information
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Who: Gustov Kirchoff, Robert Bunsen |
When: 1860 |
Where: Germany |
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Name Origin
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Latin: caesius (sky blue); its salts turn flames blue. |
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Sources
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Found in pollucite and as trace in lepidolite. |
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Uses
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Used as a 'getter' to remove air traces in vacuum tubes. Since it ionizes readily, it is used as an ion rocket motor propellant.
Also used in photoelectric cells, atomic clocks, infrared lamps.
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Radioactive isotopes of caesium are used in the medical field to treat certain types of cancer.
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This metal is also used in photoelectric cells due to its ready emission of electrons.
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Notes
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Also know as cesium in the United States. |
Along with gallium, francium and mercury, caesium is among the only metals that are liquid at or near room temperature. Caesium reacts explosively in cold water and
also reacts with ice at temperatures above -116'C.
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Caesium has at least 39 known isotopes which is more than any other element, except francium. Although only one of these is naturally occurring and stable, Cs-133.
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Caesium is considered highly toxic. |
Caesium is most notably used in atomic clocks, which are accurate to seconds in many thousands of years. SI defines the second
as (exactly) 9,192,631,770 cycles of the radiation which corresponds to the transition between two energy levels of the ground state of the 133Cs atom.
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