Elements Matter - Helium
- Veena Patwardhan - Special Correspondent
The second in this new series covers the little known aspects and stories on helium.
What do party balloons, space shuttles, MRI machines, and the Large Hadron Collider have in common? They all need helium. Whether in the gaseous or liquid form, at room temperature or at temperatures close to absolute zero, the world consumes around 8 billion cubic feet of helium each year for various purposes.
After hydrogen, helium is the second most abundant element in the universe, and having an atom with two protons, two neutrons, and two electrons, is also the second simplest of the chemical elements. It is the lightest of the noble gases and completely inert.
Helium has some fascinating physical properties. Of all the elements, it’s boiling point −452.1°F (−268.9°C) and melting point −458°F (−272.2°C) are the lowest. As is evident from these figures, helium remains a gas even at very low temperatures, and is in the liquid state over a very short temperature range. Just above its melting point, at a temperature of about -27271°C (-456°F), it becomes a superfluid, that is, it flows upwards out of a container defying the force of gravity. Helium is also the only element that cannot be solidified just bby lowering the temperature a at ordinary pressures. To solidify it, the pressure too has to be increased. These peculiar properties of helium make it an important element in low-temperature research.
History of the ‘Sun’ element
The most fascinating fact about the history of this noblest oof gases is that it was discovered twice. First around 92,900,000 miles away from our planet – in the Sun, and only around three decades later on
On a visit to Guntur, India, to observe the solar eclipse on 18th August,1868, the
French astronomer Pierre Jules César Janssen studied the spectral lines of the solar prominences and realised they were bright enough to be studied even in normal daylight. So, the next day, he studied the chromosphere of the sun again through his spectroscope and discovered a yellow spectral line close to those of sodium, but distinct from them. He concluded it must be from some unknown element in the Sun. Around two months later, on 20th October, a British astronomer Sir Joseph Norman Lockyer discovered the same spectral line observing the Sun’s spectrum through a more powerful spectroscope and even measured its wavelength (587.49 nanometres). Realising it did not match that of any other known element on earth, he and an English chemist Edward Frankland named the element helium after the Greek word for the Sun and the Sun God - Hēlios. And so, both Janssen and Lockyer are credited with first discovering extraterrestrial helium.
For quite some time afterwards, it was believed helium only existed in the Sun. Till in 1895, the Scottish chemist Sir William Ramsay discovered trace amounts of helium gas in cleveite, a mineral containing uranium, while trying to produce argon from it. Lockyer confirmed it was indeed helium. Around the same time, Swedish chemist Per Teodor Cleve and his student Nils Abraham Langlet also independently discovered helium in the same mineral. Thus, cleveite became the first known earthly source of helium. Actually, Lockyer had called the new element helium assuming it to be a metal. Later, Ramsay had suggested he re-name it as ‘helion’ to go with the names of the other noble gases. But Lockyer refused and so the name stayed unchanged.
Then, on December 7, 1905, after two years of research in their laboratory in Kansas University’s Bailey Hall, chemistry professors Hamilton P. Cady and David F. McFarland made a significant discovery.
They found that the samples of the strange non-flammable gas collected from a natural gas field in Dexter, Kansas, that they had been working on, contained considerable amounts of helium. Their work re- vealed that natural gas was a much better source for extracting helium as compared to cleveite. Bailey Hall, the site of this significant breakthrough, bears a plaque from the American Chemical Society honouring the building as a National Chemical Historical Landmark. This discovery also led to the detection of a massive reserve of helium below the American Great Plains and to the United States becoming the sole supplier of helium to the rest of the world.
From helping launch rockets to saving lives
Helium’s interesting properties have been fully exploited for multiple applications. The earliest use of helium in large quantities was for buoying balloons and airships. Non-flammable helium-filled airships helped win World War II by detecting the presence of German submarines in the Atlantic and guiding US supply and troop ships safely through dangerous waters. Helium was used to support the production of atomic energy and played a significant role in the making of the atomic bomb at Los Alamos, New Mexico.
A major use of helium today is for Magnetic Resonance Imaging (MRI) machines. These machines, used for diagnosing various medical conditions such as cancers, tumours, brain illnesses and heart damage, need liquid helium for cooling the superconducting magnet that provides their magnetic field. Helium also helps create an inert atmosphere for welding processes, facilitating the fabrication of magnesium and other metals. Space shuttles need liquid helium to clean out
their liquid hydrogen and oxygen fuel tanks, and also to pressurise the interior of liquid fuel rockets, besides condensing hydrogen and oxygen to make rocket fuel and forcing the fuel into the engines during rocket launches. Being in the liquid state even at -270°C, helium is cold enough to be used in superconducting devices such as sensitive optical devices and detectors of magnetic fields.
Besides, helium is also used in leak-detection systems, for preparing the helium-neon gas lasers used in supermarket check-outs for scanning bar codes, for preparing helium-oxygen mixtures that deep-sea divers can breathe comfortably, and for creating an inert atmosphere for manufacturing fibre optic cables used for internet supply and cable TV and growing ultrapure crystals for silicon wafers. Now, research is underway for using it as a coolant in next- generation nuclear power plants. An incredible number of applications for an inert gas, one would think.
No longer the disappearing element?
For some time now, scientists have been predicting the world could soon run out of helium, a non-renewable resource. Currently, we have no way of manufacturing it. And once used for as a coolant or for other purposes, we cannot recycle it. Being lighter than air, it immediately rises into the atmosphere and escapes into space. All the helium we have is trapped in the earth’s crust.
And while it’s not possible to estimate the exact amount of helium deep within the earth’s crust, we do know it is formed when radioactive elements like uranium and thorium present in rocks deep beneath the earth’s surface decay, and then it accumulates in pockets in the crust or in reservoirs of natural gas. When wells are dug for collecting the natural gas, helium gas, that also comes to the surface, gets released and escapes into space.
Recently, geologists from the Universities of Oxford and Durham found that volcanic activity releases helium from deep down in the Earth into shallower pockets closer to its surface. Accordingly, they began looking for such helium pockets and found a huge reservoir of the gas in the Tanzanian East African Rift Valley in June last year. Initially estimated to be 54 billion cubic feet (approximately eight times the annual global demand), recent analysis of the helium deposit has revealed it could be much bigger - around 98.6 billion cubic feet.
Many researchers and geologists have referred to the new find as ‘life-saving’ and as a ‘game-changer’, and are of the view that many more massive helium reservoirs could be unearthed in other parts of the world. After the earlier scares, that’s good news indeed. Good enough to lift our spirits!
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2. Biman B. Nath: The Story of Helium and the Birth of Astrophysics - Springer Science & Business Media, 10 Nov 2012
3. John H. McCool: High on Helium - University of Kansas, www.kuhistory.com
4. Francie Diep: 8 Surprising High-Tech Uses for Helium - Innovation News Daily, www.nbcnews.com , 18 May 2012
5. Helen Briggs: Helium discovery a ‘game-changer’ - www. bbc.com , 28 June 2016
6. Matthew Gunther: Scientists unearth one of the world’s largest helium deposits - Chemistry World, 30 June 2016
7. Michelle Starr: Massive ‘life-saving’ helium field just turned out to be far bigger than we’d hoped – www.sciencealert.com , 10 October 2017
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