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The Weakest Link: Bonding between Helium Atoms

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Lawrence L. Lohr and S. M. Blinder

Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055

J. Chem. Educ., 2007, 84 (5), p 860

DOI: 10.1021/ed084p860

Publication Date (Web): May 1, 2007

Section:

History, Education, and Documentation

Abstract

Van der Waals attraction between helium atoms can lead to the formation of weakly-bound He₂ diatomic molecules stable at temperatures in the millikelvin range. Helium dimers were first detected experimentally in 1993 and 1994. Sophisticated quantum-mechanical computations confirm that the He–He bond is the weakest known, with a binding energy corresponding to 1.176 mK, about 10^-4 eV. The average internuclear distance is computed to be in excess of 50 Å, which makes He₂ the largest known diatomic molecule as well. The authors have introduced an idealized deltafunction model for the helium dimer that succinctly represents its remarkable properties. Despite the weakness of each individual He–He bond, an intriguing mechanism exists for helium to form trimers and larger clusters with much greater binding energies.

Keywords (Audience):

Graduate Education / Research

Keywords (Domain):

Physical Chemistry

Keywords (Pedagogy):

Textbooks / Reference Books

Keywords (Subject):

Atomic Properties / Structure

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This article has been cited by 1 ACS Journal articles (1 most recent appear below).

A New "Bottom-Up" Framework for Teaching Chemical Bonding
Leeor Kronik , Tami Levy Nahum , Rachel Mamlok-Naaman and Avi Hofstein
Journal of Chemical Education2008 85 (12), 1680
- A New "Bottom-Up" Framework for Teaching Chemical Bonding
  Leeor Kronik , Tami Levy Nahum , Rachel Mamlok-Naaman and Avi Hofstein
  Journal of Chemical Education2008 85 (12), 1680
  Traditional curriculum for teaching bonding often fosters the use of over-simplifications and over-generalizations. Therefore, there is a need for a presentation that is consistent with current scientific knowledge and that provides the student with the ...
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