Weak attractive forces between molecules. When a simple covalent substance melts or boils, it is these forces that are broken (not the covalent bonds in each molecule).

Electrons that are not attached to a particular atom.

E.g. in a metal, outer electrons can be free to move through the solid.

When electrons are lost by one atom and gained by another, so that they both get full outer shells.

A type of covalent bond where four electrons (two pairs) are shared between two atoms.

The "properties" of a material are...

Substances where all atoms are linked together in a regular structure, with strong covalent bonds between them (e.g. diamond).

Different structures of the same element.

Substances which are made up of small covalent molecules, which are held together by weak intermolecular forces (e.g. water).

A molecule made up of 60 covalently bonded carbon atoms arranged to form a hollow sphere.