What is Helium?

            Most of the gases found in nature can be prepared in the laboratory. But there are a few gases that are found only in nature. Helium is one such gas. It is an inert gas, which is odorless and tasteless. Due to its unusual characteristics, helium is a very useful gas. It is the second lightest gas, next to hydrogen but unlike hydrogen, it is non inflammable.
The characteristics of Helium

            An English scientist sir Joseph Norman Lockyer and a French chemist, Pierre Janssen, independently discovered helium gas in 1868.

            While studying the solar spectrum to find the elements present in the sun, they came across some lines that were not observed earlier. These lines suggested the presence of a new element in the sun. This element was named helium, after the Greek word ‘Helios’ meaning the sun. A number of scientists tried to detect the presence of helium in the earth’s atmosphere. They detected very small quantities of helium in the atmosphere. Did you know that atmospheric air contains only one part of helium in 1,86,000 parts, i.e., 0.0005239%?

            Due to its lightness and non inflammability, helium is used in weather balloons. Helium is also used to ease the breathing difficulties of asthmatic patients. Deep sea divers are given a mixture of oxygen and helium for breathing so that after coming back, they do not suffer form the bends. Helium is also used to weld aluminum. A mixture of helium and neon is used to produce laser beams. Helium can be liquefied at -268.90 degree centigrade or 4.2 K. liquid helium is used in low temperature work.