Hey! Can i just check that bond dissociation enthalpy occurs when ONE MOLE of gaseous bonds are broken forming gaseous atoms. And enthalpy change of atomisation occurs when ONE MOLE of gaseous atoms are formed from element in their standard state?? For in my booklet its written down that Cl2(g) to 2Cl(g) is enthalpy of atomisation and I thought because two moles are formed it would be bond dissociation enthalpy as enthalpy of atomisation for chlorine would instead be 1/2 Cl2(g)-->Cl(g). Thanks for the help, hopefully ive explained it clearly.