Of all the elements of the periodic table, helium is the least reactive. It does not react with water, acids, halogens, bases or air.
Helium is a gas that belongs to the noble gas family. It is colorless and has the chemical symbol He. This element has a low boiling point of -268.93 degrees Celsius and a melting point of -272.2 degrees Celsius.
In 1868, Pierre Janssen was the first to suspect that a new element existed during his observation of a solar eclipse. He named this element helium. However, it was William Ramsay in 1895 that discovered the presence of helium on earth in a uranium mineral.
At present, the uses of helium include superconductive instruments, welding and as a cryogenic coolant.