Cesium

Phuong Nguyen Period 6 =Ce **sium **= My element is Cesium. Cesium is a one of chemical element in periodic table. This is the detail of cesium:
 * Element name : Cesium or Ceasium
 * Symbol : Cs
 * Group : 1
 * Period : 6
 * Atomic Number : 55
 * Atomic Mass : 132.9055
 * Number of protons : 55
 * Number of neutrons : 78
 * Most common isotope : Cs with the proton is 55 and the mass is 133
 * Electron configuration : [Xe]6s1

Cesium belong to alkali metal group. About appearance, it is a soft metal with a silver-gold color. It is easy to melt at only 83 degrees Faherenheit, but it is solid at room temperature 68 degrees Faherenheit. Cesium has lowest. Ionizing radiation varies in the degree of damage it can do to living tissue, the most dangerous types can mutate DNA. There are three ionizing radiation : Alpha Decay, Beta Decay, Gamma Decay. Cesium has a lowest ionizing power so it belongs to Gamma Decay. It is electromagetic radiation, not a particle, it has no mass or no charge and does bit change the compositionof the nucleus. Cesium belongs Gamma Decay because it has too much energy.
 * 1) __**Physical Properties :**__

2. __**Chemical Properties:**__ The chemical properties of Cesium are revealed during a reaction with another element or substance Cesium reacts violently with cold water and ice down to a temperature of 177 degrees Faherenheit. Especially, Pure Cesium has to be stored in an airtight container to keep it from contacting water. Besides, cesium is typically sold in the form of the much more stable compound cesiumazide (CsN3). When Cesium combine with hydroxide ( CsOH) is called Cesium hydroxide, it rapidly attacks glass. Cesium reacts very quickly in the presence of oxygen. So, it must be stored in an inert, dry environment or put it in oil or kerosene.

3. __**History :**__ Cesium was discovered by Robert Bunsen and Gustav Kirchhoff in 1860. It was found in mineral water in Germany. It was a first element discovered by spectrum analysis- is a method of charting and analyzing the chemical properties of matter and gasses. If Cesium got it's name, it was because it is a spectrum containing two bright lines in the blue and from the Latin //ceasius// which mean "bluish gray". Most of important use for casium has been in research and development.

4. **__Use :__** Cesium is used in atomic clocks. It is very useful for human life. The cesium atomic clock is a devide that uses as a reference exactly frequency of the microwave. Besides, it also used as a catalyst to create certain desired chemical reactions. Cesium is useful in medical too. Some radioactive isotopes of cesium is used highly in cancer treatment. Beside the medical field, Cesium also is used widely in the construction in industry such as dectect liquid flow in pipes and tanks, measuring thickness of sheet metal, paper, film and many other products. So, some kinds of Cesium is very expensive.

5. **__Common Forms :__** The most common form of Cesium is Cesium-137. Besides,it has another fairly common radioisotope is Cesium-134, but Cesium-137 is more common and more significant as a environmental contaminant than Cesium-134. Compound is a substances made up of 2 or more elements chemically bonded. So, Cesium has lots of compounds. But there are 4 common Cesium compounds that people found them, they are Cs2CO3, CsCL, CsOH and Cs2O. They are also used widely in industry and it is very necessary to human life in many fileds. Cesium-137 is found on erath.

6. **__Isotopes :__** Cesium has at least 39 known isotopes. The atomic masses of these isotopes range from 112 to 151. It has only one occurring stable isotope: Cs- 133 because it alway has 78 neutrons and does not have half-life. And most of the other isotopes have half-lives from a few days to fractions of a second. There are 11 main radioactive isotopes but only three have half-lives long enough to warrant concern. They are Cs-134, Cs-135, Cs-137. Actually, Cesium is naturally present as the isotope Cs-133. They are produced by nuclear fission.

7. **__Bibliography :__**

**this is a cesium clock in the past** //__http://tf.nist.gov/cesium/atomichistory.htm__//

**this is a cesium clock in present**

__//http://www.periodictable.com/Samples/055.x1/index.s12.html//__

__//http://www.americanelements.com/csm.html//__