A fullerene is any molecule composed entirely of carbon, and can take the form of hollow spheres, ellipsoids, or tubes. Spherical fullerenes (often referred to as "buckyballs") are one of the known structurally different form of carbon. C60 are the most common of buckyball structures.
The nucleus-to-nucleus diameter of a C60 molecule is approximately 0.71 nm. The C60 molecule has two bond lengths; The 6:6 ring bonds (between two hexagons) can be considered "double bonds" and are shorter than the 6:5 bonds (found between a hexagon and a pentagon). The average bond length of a C60 molecule is 1.4 angstroms. In recent years, the chemical and physical properties of fullerenes have been a widely discussed topic in nanotechnology research and development.