enthalpy

• lattice enthalpy of formation: the enthalpy change when one mole of a solid ionic compound is formed from it's gaseous ions under standard conditions
• enthalpy change of 1st ionisation: the enthalpy change when one mole of gaseous 1+ ions are made from one mole of gaseous atoms
• enthalpy change of hydration: enthalpy change when one mole of gaseous ions is dissolved in water
• enthalpy change of solution: enthalpy change when one mole of solute is dissolved in a solvent
• when a solid ionic lattic dissolves in water:

  • bonds between ions break to give gaseous ions (endothermic process, negative / opposite of lattice enthalpy)
  • bonds between ions and water are made (exothermic, enthalpy change of hydration)
• how does ionic charge affect enthalpy of hydration?

  • increased charge
  • stronger attraction to water
  • releases more energy when bonds are made
  • more exothermic
• how does ionic radius affect enthalpy of hydration?

  • smaller ion
  • increased charge density
  • stronger attraction to water
  • more exothermic
• how does size of charge on ion affect ionic bonding?

  • increased charge, stronger electrostatic attraction
  • more energy required to overcome these forces
• how does size of ion affect strength of ionic bond?

  • smaller ion, pack closer together
  • stronger electrostatic attraction
  • more energy required to overcome forces
• first electron affinity: enthalpy change when one mole of gaseous 1- ions are made from one mole of gaseous atoms