Entity: CAESIUM
Caesium is a soft, silvery-golden alkali metal with symbol Cs and atomic number 55. It is the most electropositive metal and occurs in pollucite and lepidolite. Caesium-137, a radioisotope with a half-life of 30.2 years, is used in radiotherapy.
CAESIUM
Etymology
The name 'caesium' is derived from the Latin word 'caesius', meaning sky-blue, due to the blue lines in its spectrum.
Definition
Caesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal that is the most electropositive metal.
Historical Context
Caesium was discovered spectroscopically in 1860 by German scientists Robert Bunsen and Gustav Kirchhoff. It was the first element to be discovered using this method.
Cultural Significance
Caesium is used in various applications, including photocells and radiotherapy. Its radioisotope, caesium-137, plays a crucial role in medical treatments.
Related Concepts
Caesium is part of Group 1 (alkali metals) in the periodic table. It is known for its unique properties, such as being one of the few elemental metals that are liquid at room temperature.
See Also
A ductile silvery-white element of the alkali metal group that is the most electropositive metal. It is used in photocells and has a radioisotope, caesium-137, used in radiotherapy.