Article
Article
Liquid helium
Article By:
Shivaram, Bellave S. Department of Physics, John S. Beams Laboratory, University of Virginia, Charlottesville, Virginia.
Last reviewed:January 2020
DOI:https://doi.org/10.1036/1097-8542.386400
Helium at an absolute temperature so low that it assumes a liquid state. Helium boils at a substantially lower temperature, 4.2 K (−452°F or −269°C), than any other substance; and below 2.172 K (−455.76°F) the liquid exhibits the extraordinary properties of superfluidity, notably the ability to flow through narrow channels with complete absence of friction. In addition to the common isotope of atomic weight 4, helium has a rare isotope of atomic weight 3 with a normal boiling point of 3.2 K (−454°F) and a superfluid transition at a very much lower temperature near 0.001 K. Both forms of helium remain in a liquid state at absolute zero. All of these characteristics are due to the weakness of the attractive force between two helium atoms and to the small atomic mass, which according to the laws of quantum mechanics makes the atoms difficult to localize.
The content above is only an excerpt.
About AccessScience
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information
