| Cesium |
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| Atomic Number - | 55 | Melting Point (°C,°F) - | 28.44 °C, 83.19 °F |
| Atomic Symbol - | Cs | Boiling Point (°C,°F) - | 671 °C, 1240 °F |
| Atomic Mass - | 132.9 | Electron Configuration - | [Xe] 6s1 |
| Group - | 1 | Electrons Per Shell - | 2, 8, 18, 18, 8, 1 |
| Period - | 6 | Protons - | 55 |
| Series - | Alkali Metals | Neutrons - | 78 |
| Block - | d-block | | |
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Element Description - Caesium (also cesium in the United States) pronounced /?si?zi?m/; is a chemical element in the periodic table that has the symbol Cs and atomic number 55. It is a soft silvery-gold alkali metal which is one of at least three metals that are liquid at or near room temperature. This element is most notably used in atomic clocks.
The variant spelling cesium is sometimes used, especially in North American English, but caesium is the spelling used by the IUPAC, although since 1993 it has recognized cesium as a variant as well. |
Element Characteristics - The electromagnetic spectrum of caesium has two bright lines in the blue part of the spectrum along with several other lines in the red, yellow, and green. This metal is silvery gold in color and is both soft and ductile. Caesium is also the most electropositive and most alkaline of the stable chemical elements and also has the least ionization potential of all the elements, except for francium. Caesium is the least abundant of the five non-radioactive alkali metals. (Technically, francium is the least common alkali metal, but since it is highly radioactive with less than 30 grams in the entire earth at one time, its abundance can be considered zero in practical terms.)
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. Caesium hydroxide (CsOH) is a very strong base and will rapidly etch the surface of glass.
There is an account that caesium, reacting with fluorine, takes up more fluorine that it stoichometrically should. It could be that, after the salt Cs+F− has formed, the Cs+ ion, which has the same electronic structure as xenon, acts like xenon and forms a covalent fluoride such as Cs+F2. |
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