Ionisation Energy

• Ionisation energy - the amount of energy needed to remove 1 electron from a gaseous atom by breaking the electrostatic attraction
• 1st Ionisation Energy - energy required to remove 1 mole of electrons from one mole of gaseous atoms to make one mole of gaseous +1 ion
• 2nd Ionisation Energy - energy required to remove one mole of electrons from one mole of gaseous +1 to make 1 mole of gaseous +2 ions
• what is the trend of ionisation energy across period 3?

  Ionisation energy increases as you go across the period

  due to nuclear charge increasing

  atomic radius increasing

  similar shielding due to the same number of shells

  therefore electrons are attracted more strongly and are harder to remove