Animation showing methane molecules. Each molecule is colour-coded to show its polarity. Methane is a symmetrical molecule, which makes it non-polar: there is separation of electric charge over its surface. This phenomenon means the individual molecules do not attract each other strongly, which is responsible for many of its physical properties, such as its low boiling point. Its boiling point, -161.5 degrees Celsius, is shown at bottom right. Compare this situation with that of the similar compounds water and ammonia, in clips K004 4333 and K004 4338.