Enthalpy of atomization
= Enthalpy of atomization
{title2=$\Delta H_{\rm at}^{\circ}$}
An <enthalpy of atomization> is the <enthalpy> change for making one <mole> of separated gaseous <chemical atoms> from a specified starting <chemical substance>. For <sodium>, the relevant step is <sublimation> to monatomic <gas>; for diatomic <chlorine>, it is half the compatible molar <bond-dissociation energy> expressed as an <enthalpy>.