Ionisation Energies

• What is Ionisation?

  the removal of one or more electrons
• Definition of the First Ionisation Energy?

  The energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of 1+ gaseous ions
• What are the Fcators affecting Ionisation energy?

  nuclear charge, atomic radius and shielding
• what is nuclear charge?

  more protons, the more positively charges the nucleus is and stronger the attraction
• what is Atomic Radius?


  An electron close to the nucleus will be much more strongly attracted
• What is Shielding?

  the more electrons, the more shields
• What happens to the Ionisation Energy down a group?

  Gets easier to remove electrons
• What happens to the Ionisation Energy down the Group?


  decreases, it is easier for the electrons to be removed, the elements further down the group have extra electron shells- increase in shielding, as well as the atomic radius increases so is larger, and the Nuclear charge increases
• What happens to the ionisation energy across a period?

  ionisation energy increases, it is harder to remove electrons, the number of protons is increasing- meaning the positive charge of the nucleus increases and the electrons are pulled closer to the nucleus, the atomic radius is smaller and the shield doesnt change
• why is it different between group 2 and 3?

  theres a drop of ionisation energy, as 3 is in the P-orbital and 2 is in the S-orbital, the P-orbital has a slightly higher energy with additional shielding
• why is it different between group 5 and 6?

  group 5 theres an electron being removed from a singly occupied orbital but in group 6 theres an orbital containing 2 electrons- therefore causing a repulsion called the P-orbital repulsion