We know that all substances have different melting and boiling points, for example the boiling point of ethanol is 78°C but boiling point of water is 100°C (assuming we are talking about RTP values). The amount of energy needed for a substance to change state depends on the strength of the forces acting between the particles of substance, now we are not talking about chemical bonds here, but weaker forces which cause an attraction between atoms and molecules but, which when broken, do not alter the chemical composition of the substance.


So what exactly are these forces?