key definitions

• bond enthalpy 


  the amount of energy needed to break 1 mole of covalent bonds.
• 1st ionisation energy (ΔHθI1)

  the minimum amount of energy needed to remove 1 electron from 1 mole of gaseous atoms to create 1 mole of 1+ ions.
• 1st electron affinity (ΔHθEA)

  the enthalpy change when 1 mole of gaseous atoms are converted to 1 mole of negatively charged gaseous ions.
• enthalpy of lattice formation (ΔHfθ)

  the enthalpy change that occurs when 1 mole of a solid ionic compound is formed from its gaseous ions.
• The enthalpy of lattice dissociation 


  the enthalpy change needed to separate 1 mole of an ionic substance from its gaseous ions.
• enthalpy change of solution (ΔHθsoln) 

  
  

  the enthalpy change that occurs when 1 mole of an ionic solid is dissolved completely in a sufficient volume of solvent to form a solution.
• enthalpy of hydration (ΔHθhyd)


  the enthalpy change when 1 mole of separated gaseous ions is dissolved completely in water to form 1 mole of aqueous ions.
• The standard molar enthalpy of atomisation (ΔHθat)

  the enthalpy change for the formation of 1 mole of gaseous atoms from 1 mole of the element in its standard state under standard conditions.