Helium is the second most abundant element in the universe after hydrogen, yet it is a rare and non-renewable resource here on Earth. Helium exists in large quantities in the universe since it is a product of alpha decay of heavier radioactive elements and nuclear fusion in stars. However, on Earth, most of our helium is formed from the natural radioactive decay of heavy elements contained in rocks. Helium’s unique properties have led to its wide variety of commercial and scientific applications. In this article, we explore helium’s physical and chemical properties, current applications and concerns around its scarcity.
Physical and Chemical Properties of Helium
Helium is unique as the only element that remains a gas across all temperatures except below 0.95 K where it becomes a liquid. As a noble gas, it does not react chemically with any other element which makes it quite stable and inert. Helium’s low boiling point of 4.222 K and freezing point of 0.95 K allow it to be liquified easily. While gaseous helium is colorless, odorless and weakly paramagnetic, liquid helium is transparent and appears similar to water in appearance.
Some key physical properties of helium that make it highly useful include its extremely low density of 0.2 grams per liter (at STP), making it less dense than air. It has a high specific heat capacity and heat conductivity. Most importantly, helium has the lowest liquefaction temperature of all elements, approaching absolute zero. These unique physical attributes have enabled the widespread use of both gaseous and liquid helium.
Major Applications of Helium
– Balloons and Party Supplies: The low density and low reactivity of helium makes it safely inflatable for balloons, blimps and other party supplies. It is the standard filling gas for weather balloons, party balloons and lighter-than-air toys.
– Welding and Semiconductor Manufacturing: An inert atmosphere of helium protects sensitive materials and components from oxidation during high temperature processes like arc welding, cutting and melting of reactive metals. It is used in growing crystals and fabricating computer chips.
– MRI and NMR Technology: Helium’s paramagnetic properties allow it to be used as a refrigerant in NMR/MRI machines. Liquid helium cools superconducting magnets to temperatures near absolute zero, enabling high resolution medical imaging.
– Rocketry: The low density and inert nature of helium makes it an ideal gas for inflation/pressurization systems in military and space rockets, balloons and aircraft. It maximizes payload capacity for its mass.
– Cryogenics: Liquid helium is indispensable as a refrigerant for achieving and maintaining extremely low cryogenic temperatures required for superconductors in medical equipment, particle accelerators and research. Its freezing point of 0.95 K is the lowest among all elements.
– Fiber Optic Cables: The manufacture of preform rods and drawing of optical fibers requires an ultra-pure inert gas, for which helium’s passive properties make it perfect. It protects precious silica from crystallization.
Growing Scarcity and Need for Conservation
Gaseous and Liquid Helium production is a limited resource as it is a non-renewable atomic element on human timescales. While abundant in the universe, on Earth supplies come from underground reservoirs that are slowly depleted without regeneration. The United States has historically been the largest supplier through its Federal Helium Reserve which is running low and has led to sharp price increases in the last decade. As per U.S. Geological Survey, global reserves may last no more than 75 years at current production and demand rates.
There is a need to better capture and reuse helium from MRI machines, fiber optics manufacturing, welding and semiconductor industries through refinement processes. Major efforts are also underway to produce artificial sources of helium through nuclear fusion or transmutation of lithium. Conservation measures adopted by scientists include switching to alternative gases like hydrogen or nitrogen where appropriate. Considering helium’s indispensable applications, ensuring its long term availability through sustainable practices is vital for science and technology.
In , helium has unparalleled physical properties that distinguish it as a unique and irreplaceable resource for numerous modern day applications. While abundantly available in space, its scarcity on Earth necessitates judicious and responsible usage to conserve limited supplies. Continued research on renewable helium sources and improvement in recycling networks will be crucial to safeguard this valuable yet fragile element that has myriad commercial and scientific applications. Careful planning and innovation are required to secure helium’s provision for future generations.