Covalent Bonding

All molecules have covalent bonds and are usually made from the atoms of nonmetals. A pair of electrons is shared in each covalent bond to achieve a full stable outer shell for each atom.

A methane molecule has one carbon atom and four hydrogen atoms. There are four covalent bonds, one for each C-H bond, i.e. four pairs of shared electrons. The molecule forms a tetrahedron shape with a hydrogen atom at each vertex of a triangular based pyramid.

Covalent compounds have weak forces between the molecules so they are usually gases or liquids and have low melting and boiling points.