When one thinks of the well-known element, helium, images of shiny balloons and squeaky voices usually enter their heads. Helium is, however, much more diverse than that. Helium, which is the second element listed on the Periodic Table has a long, conflicting history, unique characteristics and properties, and a variety of modern, practical uses.
Helium is a colorless, odorless, and tasteless gas. Its chemical symbol is He. The atomic number of helium is two, and its atomic weight is 4.0026. Helium takes a liquid state when it is cooled to -268.6 degrees Celsius, which is approximately four degrees Celsius above absolute zero. Helium is the only known element that cannot be changed in to a solid by being cooled alone. It must also be compressed when it is being cooled. The element freezes at -272 degrees Celsius when under a pressure of twenty-six times its atmospheric pressure. Helium is called an inert gas, or a noble gas. This is because it does not combine with any of the other elements. Helium cannot be burned.
The element that is now known as helium was first sighted by the scientist Pierre-Jules Cesar Jansser in 1868. The sighting occurred when Jansser traveled to India to view a total eclipse of the sun through a spectroscope and make the first spectroscopic study of the sun’s chromosphere. During his study he observed a yellow line in the spectroscope that did not coincide with the D-line of sodium, and that he could not reproduce in a laboratory. Sir Norman Lockyer discovered at a later date that the line did not belong to any known element (4) and named it helium, from the Greek work helios, meaning “sun”. For approximately a quarter of a century helium remained a hypothetical element that was often doubted and ridiculed by spectroscopists. Most scientists of that time considered it to be an element that possibly existed in the sun’s atmosphere, but could not be found on Earth. In 1887 L. Palmieri detected helium in a yellow amorphous sublimination product from Mt. Vesuvius. Further tests on the substance proved that the element did, in fact, exist on earth.
Helium was thought to be a very rare gas until the year 1915. During that period the University of Kansas bought acreage in Kansas and did testing on what is now refereed to as a “helium plant.” When it was found that all of the specimens tested contained helium, and that the element was readily available the price of helium immediately fell from $2,500 per cubic foot to three cents per cubic foot. Today helium is widely known and is the second most abundant element in the universe.
Liquid helium, which is sometimes considered to be the strangest of all liquids, behaves differently. Unlike most liquids liquid helium conducts heat extremely well, it flows toward warm places, and expands rather than contracting when it is cooled. Liquid helium forms a thin film over everything that it touches, and can be used as a siphon.
Helium has a very wide array of uses. About seven hundred million cubic feet of helium are used in the United States each year. Helium is most widely known for its use in balloons such as novelty balloons, meteorological balloons, and hot air balloons. In air, helium has ninety-two percent the lifting ability as hydrogen, but helium is much safer because it will not burn, as hydrogen will. The United States Government uses helium chiefly to maintain the proper amount of pressure in rocket fuel tanks during flight. If the proper pressure is not kept the walls of the fuel tank will collapse as the fuel drains in to it. The largest industrial use of helium is in heliarc welding, a type of electric arc welding. The helium keeps oxygen away from the metal. Oxygen could cause the metal to corrode or burn. Helium is also used to keep chemicals from reacting with other elements during storage, transportation, and handling.
Helium is often used mixed with oxygen for breathing. It used by people who have breathing difficulties such as a person who suffers from asthma. The mixture will enter the lungs more easily because helium atoms are lighter than the nitrogen molecules of the air. Scuba divers who reach depths below one hundred feet also breathe the mixture. The helium helps the divers avoid a mixture known as nitrogen narcosis, which causes divers to lose the ability to think clearly, and they are likely to do dangerous things.
Helium is now a very widely known element, and is one of the most commonly found elements on earth. In addition to being one of the two elements that makes us the sun and stars it has a wide variety of uses.
