Cesium

=**Cesium**=


 * Atomic Number:**55


 * Protons:** 55


 * Electrons:**55


 * Neutrons:** 78


 * Average Atomic Mass:** 132.905 amu


 * Isotopes**: Cs-129, Cs-130, Cs-131, Cs-132 ,Cs-133, Cs-134, Cs-135, Cs-136, Cs-137


 * Discovery**: Cesium was discovered by Gustav Kirchhoff, Robert Bunsen at 1860 in Germany.


 * Name:** The name Cesium comes from the Latin word Caesius meaning sky blue.


 * Uses:** used as a catalyst in the hydrogenation of a few organic compounds
 * the metal can be used in ion propulsion systems. Although not usable in the earth's atmosphere, 1 kg of Cesium in outer space could propel a vehicle 140 times as far as the burning of the same amount of any known liquid or solid.
 * used in atomic clocks
 * because of its high oxygen affinity, the metal is used as a "getter" in electron tubes
 * used in photoelectric cells and vacuum tubes
 * IR lamps


 * Interesting Facts****:** Cesium (spelled Caesium in the UK) is the most electropositive of all naturally occurring elements; in other words, is the very reactive.

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 * Video:**


 * Sources:**
 * Photo: [|PowerTube my Maury McCown on Flickr]
 * Video**:** [|Cesium from Periodic Videos on YouTube]
 * [|History of Cesium on WebElements]
 * [|Cesium on WebElements>]
 * [|Isotopes of Cesium on WebElements]