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:
1. Beryllium
Beryllium was discovered by Louis-Nicholas Vanquelin during 1798, in France.
Uses: Precious forms of beryl include aquamarine, morganite, and emerald. Beryllium is used as an alloying agent in producing beryllium copper, which is used for springs, electrical contacts, non sparkling tools, and spot-wedding electrodes. It is used in many structural components of the space shuttle and other aerospace craft. Beryllium foil is used in x-ray lithography for making integrated circuits. It is used as a reflector or moderatior in nuclear reactions. Beryllium is used in gyroscopes and computer parts.
2. Lithium
Discovery: 1817, Arfvedson (Sweden)
Uses: Lithium is used in heat transfer applications. It is used as an alloying agent, in synthesizing organic compounds, and is added to glasses and ceramics. Its high electrochemical potential makes it useful for battery anodes. Lithium chloride and lithium bromide are highly hygroscopic, so are used as drying agents. Lithium stearate is used as a high-temperature lubricant. Lithium has medical applications, as well.
Lithium is used extensively in rechargeable battery technology.
Lithium is the only alkali metal that reacts with nitrogen.
Lithium burns red in a flame test.
Lithium was first discovered in the mineral petalite (LiAlSi4O10).
Lithium is used to create the hydrogen isotope tritium through bombardment of neutrons.
3. Helium
Helium Discovery: Janssen, 1868, some sources say Sir William Ramsey, Nils Langet, P.T. Cleve 1895
Uses: Helium is widely used in cryogenic research because its boiling point is near absolute zero. It is used in the study of superconductivity, as an inert gas shield for arc welding, as a protective gas in growing silicon and germanium crystals and producing titanium and zirconium, for pressuring liquid fuel rockets, for use in magnetic resonance imaging (MRI), as a cooling medium for nuclear reactors, and as a gas for supersonic wind tunnels. A mixture of helium and oxygen is used as an artificial atmosphere for divers and others working under pressure. Helium is used for filling balloons and blimps.
SOURCES:
5. Krypton 
