The element helium makes up one quarter of the mass of the visible universe . . .
. . . but only about one millionth of one percent of Earth’s atmosphere and crust. That’s because helium is so light that — once released into the atmosphere — it escapes into outer space.
Also, helium’s an inert gas — it doesn’t bond with any other elements — so it isn’t held on Earth in chemical combinations. Just about all the helium left on Earth was produced by the radioactive decay of uranium. Helium is found trapped in underground pockets in natural gas fields in Oklahoma and Texas. There are also sizable deposits in Algeria, Qatar and Siberia.
Helium can make a balloon float. But it’s also used in state-of-the-art technologies, such as magnetic resolution imaging, or MRI, and in the manufacture of semiconductors and optical fibers. Earth’s supply of helium is limited — and, if helium isn’t removed from natural gas, it’s lost to our atmosphere — and then to space.
It’s sometimes possible to recycle helium. Also, the U.S. has a large stockpile. This year, it’ll begin to sell some of its helium to commercial helium refiners and other industrial gas companies.
Special thanks today to the Camille & Henry Dreyfus Foundation, a private foundation dedicated to advancing research and education in the chemical sciences. We’re Block and Byrd for Earth and Sky.
NOTE: The term “MRI” actually refers to “Magnetic Resonance Imaging.”
The U.S. helium end-use markets are the following:
- Breathing Mixtures: 3%
- Controlled Atmospheres: 3%
- Other: 5%
- Leak Detection: 6%
- Purge/Pressure: 8%
- Fiber Optics Manufacturing: 9%
- Lifting/Balloons: 14%
- Welding: 16%
- MRI: 18%
- Industrial/Scientific Applications: 8%
Crude helium is separated by liquefying the other gases present in the natural gas. Helium and oxygen is often supplied as a breathing mixture for deep-sea divers and caisson workers and is used in decompression chambers; because helium is less soluble in human blood than nitrogen, its use reduces the risk of caisson disease, or the “bends.”
The sun and other stars are made mostly of helium and hydrogen. The energy of these stars is produced when hydrogen atoms fuse (join together) to form helium atoms. This process is also what gives the hydrogen bomb its energy.
Properties. Helium is a colorless, odorless, and tasteless gas. Its chemical symbol is He. Its atomic number (number of protons in its nucleus) is 2. Its relative atomic mass is 4.002602. An element’s relative atomic mass equals its mass (amount of matter) divided by 1/12 of the mass of carbon 12, the most abundant form of carbon. Helium’s density is 0.1664 milligram per cubic centimeter at 20 ?C. It changes to liquid when it is cooled to -268.9 ?C, about 4 ?C above absolute zero. Helium is the only chemical element that cannot be changed to a solid by cooling alone under ordinary pressures. It must be cooled and compressed. Helium freezes solid at -272.2 ?C under a pressure of 26 times atmospheric pressure.
Liquid helium is one of the strangest of all liquids. Unlike most liquids, it conducts heat extremely well, it flows toward relatively warm places, and it expands instead of contracting when it cools. Liquid helium forms a film over everything it touches.