Periodic Table of the Elements

caesium	Atomic number: 55 Atomic weight: 132.90545 Symbol: Cs Group number: 1 Electronic configuration: [Xe].6s¹
Description General information Physical data Radii Electronegativities Solid state structure Temperatures Enthalpies Ionization Enthalpies Isotopes Further information

Description Caesium is known as cesium in the USA. The metal is characterised by a spectrum containing two bright lines in the blue (accounting for its name) along with several others in the red, yellow, and green. It is silvery white, soft, and ductile. It is the most electropositive and most alkaline element. Caesium, gallium, and mercury are the only three metals that are liquid at room temperature. Caesium reacts explosively with cold water, and reacts with ice at temperatures above -116°C. Caesium hydroxide, the strongest base known, attacks glass.
General information Discoveror: Gustav Kirchhoff, Robert Bunsen Date discovered: 1860 Discovered at: Germany Meaning of name: From the Latin word "caesius" meaning "sky blue"
Physical data Standard state: ŸµP
1st	375.7
2nd	2230

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass Accurate mass % natural abundance

¹³³Cs 133.905429 (7) 100

Further Information

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Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Cs.html