Enthalpy change, of atomisation

The standard enthalpy change of atomisation of an element, AHtt, is the enthalpy change when one mole of gaseous atoms is produced from the element in its standard state, under standard conditions. 

The standard enthalpy change of atomisation of hydrogen relates to the equation ... 

We cannot usually find the value of bond energies directly so we have to use an enthalpy cycle. The average bond energy of the C—H bond in methane can be found using the enthalpy changes of atomisation of carbon and hydrogen and the enthalpy change of combustion or formation of methane. 

There are two chloride ions in MgCl2, so the values of the enthalpy change of atomisation and the first electron affinity of chlorine must be multiplied by 2. 

A Born-Haber cycle is a type of enthalpy cycle (Hess cycle) that includes lattice energy, enthalpy change of formation and relevant electron affinities, enthalpy changes of atomisation and enthalpy changes of ionisation. 

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