Helium the second element in the periodic table after hydrogen is also the second most common element in the universe after hydrogen. High concentrations of helium are detectable within stars. On earth, however the noble gas helium is not such a common element as it makes up just 0.0005% of the earth’s atmosphere. Atoms of this light element continually escape from earth’s upper atmosphere.
Helium’s original discoverer, the French astronomer Pierre-Jules-Cesar Janssen, detected the gas in the sun by means of a spectrograph taken during a solar eclipse seen from India in 1868. Believing the gas existed only in the sun the English astronomer Sir Norman Lockyer and the chemist Professor Edward Frankland named the element after the Greek god of the sun “Helios”. In 1895, Sir William Ramsay, the discoverer of the noble gases neon, krypton and xenon, demonstrated helium’s presence on earth.
The gas forms by the decay of radioactive elements within the earth’s crust. Elements decaying by alpha decay emit alpha particles. An alpha particle consists of two protons bound together by two neutrons. In effect, an alpha particle is a helium nucleus. The positively charged alpha particle collects two negatively charged electrons to form a helium atom. The helium gas so formed seeps through cracks within the rocks to reach the earth’s atmosphere.
Although the production of the other three atmospheric noble gases (chemical properties here) relies on fractional distillation of liquid air this production method is non-economical for helium. Fortunately, there is a cheaper source of helium available. Some helium does not make it to the earth’s surface and into the atmosphere. Instead, impermeable rocks trap the gas below ground to form gas pockets. As these gas pockets also trap the important energy source natural gas, helium forms a valuable by-product from natural gas extraction. The gas fields of Texas, Oklahoma and Kansas provides over 80% of the world’s supply of helium. Other supplies of helium come from the gas fields of Algeria, Poland and Russia. India produces a small amount of the gas from extraction at thermal springs.
In addition filling party balloons Helium is important for pressurizing liquid fueled rockets in the space program. The running of MRI machines uses the liquid gas. Other scientific uses include its use as a cryogen in the study of superconductivity. Deep-sea divers avoid nitrogen narcosis by filling their tanks with a mixture of helium and oxygen.
Los Alamos National Laboratory Chemistry Division
Jefferson Laboratories Science Education website
The Helium potential of India N. K. Das, R. K. Bhandari, P. Sen and B. Sinha Current Science, Vol. 88, No. 12, 25 June 2005