Helium: Facts About the Gas
General Facts
Physical Properties
In the Environment
Where It's Found
Unusual Characteristics
 | » | Chemical symbol: He |
| » | Second lightest elemental gas, after hydrogen |
| » | Smallest of all molecules |
| » | Lowest boiling point of any element (-452.1°F, -268.9°C, 4.2 K, 7.6 R) |
| » | Seven times lighter than air |
| » | Conducts sound three times faster than air |
| » | Has five times air's thermal conductivity |
| » | Does not become radioactive under irradiation |
Physical Properties
| » | Colorless |
| » | Odorless |
| » | Tasteless |
| » | Non-toxic |
| » | Inert |
| » | Non-flammable |
| » | Slightly soluble in water |
| » | High thermal conductivity |
In the Environment
| » | Helium is produced continually by the radioactive decay of uranium and other elements, gradually working its way into the atmosphere |
| » | Helium atoms are light enough to escape the Earth's gravitational field and into space |
| » | Commercial extraction from air is impractical because helium's concentration is only about five parts per billion |
Where It's Found
| » | Commercially, helium is obtained from the small fraction of natural gas deposits that contain helium volumes of 0.3 percent or higher |
| » | Most of the world's helium comes from the Texas panhandle, Oklahoma, Kansas and the Rocky Mountains' eastern flank, other sources include the mid-east and Russia |
| » | These natural gas deposits contain more than 3,000 ppm of helium |
Unusual Characteristics
| » | At atmospheric pressure, helium becomes liquid at the lowest of all boiling points (-452°F, -269°C, 7.6 R) |
| » | Helium remains liquid to absolute zero |
| » | The coldest known substance, helium is important for cryogenic research |
| » | At 3.9 R, liquid helium exhibits super fluidity or virtually zero viscosity (Helium II), defies gravity to flow up container walls and becomes nearly a perfect heat conductor |
