"Five Elements of the Periodic Table (2)"

Continuation of the descriptions of Five Elements of the Periodic Table:

4. Cesium 

Discoverer: Gustov Kirchoff, Robert Bunsen 

Discovery Date and Location: 1860 (Germany) 

Uses: Cesium is used in atomic clocks, which are incredibly accurate. NIST-F1, America’s primary time and frequency standard, is a cesium fountain atomic clock developed at the NIST laboratories in Boulder, Colorado. NIST-F1 contributes to the international group of atomic clocks that define Coordinated Universal Time (UTC), the official world time. As scientists continue to improve its technology, uncertainty in NIST-F1′s measurement of time is continually improving. Currently it neither gains nor loses as much a second in more than 60 million years – but see strontium.
Cesium is also used in photoelectric cells and as a catalyst in the hydrogenation of organic compounds. The metal is used as a ‘getter’ in vacuum tubes.
Cesium hydroxide is used to etch silicon. 

5. Krypton 

Discovery: Sir William Ramsey, M.W. Travers, 1898 (Great Britain) 
 
Uses:
Krypton based bulbs are used in some photography applications because it produces white light under certain conditions. It is usually used in high speed flash photography.

This white discharge is also used in colored gas tubes to create a similar effect to a neon sign.

Krypton is used in the production and usage of the krypton fluoride laser, which is being used in research for nuclear fusion. It is also suitable for use in high powered laser shows.

It is mixed with argon to fill fluorescent lamps. This makes them more energy efficient by reducing the power they require. Unfortunately, this also makes this type of bulb more expensive and reduces the light output. It is also, together with xenon, used in regular light bulbs to reduce filament evaporation and allow it to operate at higher temperatures.

An isotope of krypton is used in medical scans (MRI scan) of the airways.

A measure of the wavelength of light emitted isotope of krypton was used to define the distance of a meter from 1960 to 1983. 

Uses: Cesium is used in atomic clocks, which are incredibly accurate. NIST-F1, America’s primary time and frequency standard, is a cesium fountain atomic clock developed at the NIST laboratories in Boulder, Colorado. NIST-F1 contributes to the international group of atomic clocks that define Coordinated Universal Time (UTC), the official world time. As scientists continue to improve its technology, uncertainty in NIST-F1′s measurement of time is continually improving. Currently it neither gains nor loses as much a second in more than 60 million years – but see strontium.
Cesium is also used in photoelectric cells and as a catalyst in the hydrogenation of organic compounds. The metal is used as a ‘getter’ in vacuum tubes.
Cesium hydroxide is used to etch silicon. 

SOURCES:

http://wanttoknowit.com/uses-of-krypton/ 

http://chemistry.about.com/od/elementfacts/a/cesium.htm

http://www.chemicool.com/elements/cesium.html