chem

• enthalpy formation


  One mole of a compound is formed from its in their standard state (exothermic)
• Enthalpy atomisation


  One mole of formed from its element in its standard state (endothermic)
• Bond enthalpy


  One mole of a covalent bond is broken into separate atoms in the gas state (endothermic)
• First ionisation energy


  One mole of gaseous 1+ ions is formed from gaseous atoms (endothermic)
• Second ionisation energy


  One mole of gaseous 2+ ions is formed from gaseous 1+ ions (endothermic)
• First electron affinity


  One mole of gaseous 1- is formed from gaseous atoms (exothermic)
• Second electron affinity


  One mole of gaseous 2- ions is formed from gaseous 1- ions (endothermic)
• Lattice enthalpy


  One mole of ionic lattice formed from ions in the gaseous state (exothermic)
• factors affecting lattice enthalpy 


  The greater the ionic charge and the smaller the ionic radius the more exothermic the lattice enthalpy (stronger attraction between ions)
• enthalpy change of hydration


  when one mole of gaseous ions react and gaseous ions dissolve in water
• reactivity of the halogens


  Down the group:

  More shells

  Increased shielding

  more difficult to gain an electron

  Cl2 + 2Br- = Br2 + 2Cl- (yellow solution)

  Cl2 + 2I- =. I2 + 2Cl- (orange/brown solution)