- a rare, highly reactive, soft, metallic element of the alkali metal group, used chiefly in photoelectric cells. Symbol: Cs; atomic weight: 132.905; atomic number: 55; specific gravity: 1.9 at 20°C; melts at 28.5°C.
Origin of cesium
Examples from the Web for caesium
Lithia and fluorine are each present to the extent of about 5%; rubidium and caesium are sometimes present in small amounts.
Like caesium, it is precipitated with platinic chloride, and in the ordinary course of work would be weighed as potassium.A Textbook of Assaying: For the Use of Those Connected with Mines.
Cornelius Beringer and John Jacob Beringer
It led Bunsen himself almost immediately to the isolation of two new elements of the alkali group, caesium and rubidium.
This residue consists of sodium, potassium and lithium chlorides, with small quantities of caesium and rubidium chlorides.
The platino-chlorides are reduced by hydrogen, and the caesium and rubidium chlorides extracted by water.
- a ductile silvery-white element of the alkali metal group that is the most electropositive metal. It occurs in pollucite and lepidolite and is used in photocells. The radioisotope caesium-137, with a half-life of 30.2 years, is used in radiotherapy. Symbol: Cs; atomic no: 55; atomic wt: 132.90543; valency: 1; relative density: 1.873; melting pt: 28.39±0.01°C; boiling pt: 671°C
- the usual US spelling of caesium
Word Origin and History for caesium
also caesium, rare alkaline metal, 1861, coined by Bunsen and Kirchhoff in 1860 in Modern Latin (caesium), from Latin caesius "blue-gray" (especially of eyes), in reference to the two prominent blue lines in its spectrum, by which it was first identified.
- A soft ductile metal, liquid at room temperature, the most electropositive and alkaline of the elements, used in photoelectric cells. Atomic number 55.
- A soft, ductile, silvery-white element of the alkali group. It is liquid at room temperature and is the most reactive of all metals. Cesium is used to make photoelectric cells, electron tubes, and atomic clocks. Atomic number 55; atomic weight 132.905; melting point 28.5°C; boiling point 690°C; specific gravity 1.87; valence 1. See Periodic Table.