Van der Waals Radius Definition

What Is the Van der Waals Radius in Chemistry?

The van der Waals radius is half the distance between two nonbonded atoms at their closest approach.
The van der Waals radius is half the distance between two nonbonded atoms at their closest approach. Stanislaw Pytel / Getty Images
By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on January 30, 2019

The Van der Waals radius is equal to one half the distance between two unbonded atoms when the electrostatic forces between them are balanced. In other words, it is half of the closest distance between two atoms that aren't bonded or within the same molecule. Picometers (pm) are typically the unit used to report the value.

The distance reflects the action of intermolecular forces (e.g., dipole-dipole and dispersion forces) and is related to van der Waals interactions. Knowing the van der Waals radius is helpful when predicting how closely atoms will pack to form a solid.

Sample Van der Waals Radius Values 

Element radius (pm)
H 120
B 208
C 185
N 154
O 140
F 135
Cl 180
Br 195
I 215
He 99

Reference

Housecroft. Inorganic Chemistry. 2008.

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Helmenstine, Anne Marie, Ph.D. "Van der Waals Radius Definition." ThoughtCo, Aug. 27, 2020, thoughtco.com/definition-of-van-der-waals-radius-605939. Helmenstine, Anne Marie, Ph.D. (2020, August 27). Van der Waals Radius Definition. Retrieved from https://www.thoughtco.com/definition-of-van-der-waals-radius-605939 Helmenstine, Anne Marie, Ph.D. "Van der Waals Radius Definition." ThoughtCo. https://www.thoughtco.com/definition-of-van-der-waals-radius-605939 (accessed June 10, 2023).