Van der Waals radius

The van der Waals radius, r_w, of an atom is the radius of an imaginary hard sphere which can be used to model the atom for many purposes. It is named after Johannes Diderik van der Waals, winner of the 1910 Nobel Prize in Physics, as he was the first to recognise that atoms were not simply points and to demonstrate the physical consequences of their size through the van der Waals equation of state.

Van der Waals volume

The van der Waals volume, V_w, also called the atomic volume or molecular volume, is the atomic property most directly related to the van der Waals radius. It is the volume "occupied" by an individual atom (or molecule). The van der Waals volume may be calculated if the van der Waals radii (and, for molecules, the inter-atomic distances and angles) are known. For a spherical single atom, it is the volume of a sphere whose radius is the van der Waals radius of the atom:

For a molecule, it is the volume enclosed by the van der Waals surface. The van der Waals volume of a molecule is always smaller than the sum of the van der Waals volumes of the constituent atoms: the atoms can be said to "overlap" when they form chemical bonds.

Van der Waals

Van der Waals may refer to:

People

Physics

Other uses

List of minor planets: 32001–33000

Van der Waals (crater)

Van der Waals is a lunar crater on the far side of the Moon. It is a heavily eroded feature with an irregular outer rim. The edge is lowest along the southern side where it is little more than a circular crest along the ground. It is more developed along the northern side, but the rim is notched and rugged. The satellite crater Van der Waals W is attached to the exterior of the northeast, and Van der Waals H intrudes into the rim along the southeast. The interior floor is relatively even and featureless, with only a few tiny craterlets to mark the surface.

Nearby craters of note include Clark to the north, Carver to the east, and Pikel'ner to the southeast. About two crater diameters to the west-southwest is Lebedev.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Van der Waals.

References