# Why don't we use enthalpy of fusion and enthalpy of vaporisation as two separate terms in Born-Haber's cycle?

I am not able to understand why we use enthalpy of sublimation rather than enthalpy of fusion and enthalpy of vapourisation of solid sodium metal in a Born-Haber cycle for the formation of NaCl from $sodium_{(s)}$ and $chlorine_{(g)}$ in their standard states.

Also I have rarely heard of sublimation of such metals.Is it like sublimation of camphor.

• Thermodynamically, how would you relate the enthalpy of fusion plus enthalpy of vaporization with the enthalpy of sublimation? Think about that. – Jon Custer Jul 15 '16 at 13:48
• @Jon Custer The sum may be equal to the enthalpy of sublimation.But I dont think this is the standard way of writing in textbooks.If it is written there, then it may mean that we are avoiding the liquid phase of the metal. – Sikander Jul 15 '16 at 13:50