Shells and ionisation energy

Shells and ionisation energy

1. First ionisation energy

   • the energy required to remove one electron from each atom in one mole of gaseous atoms to from one mole of gaseous +1 atoms

2. successive ionisation energy

   • measure of energy required to remove one electron in turn
   • as each electron removed, there is less repulsion between electrons and shells are more attracted to nucleus
     • distance from nucleus decreases, nuclear attraction increases
       • more ionisation energy is needed to remove each electron

3. factors affecting ionisation energy

   • Nuclear charge
     • the greater the nuclear charge, the bigger the attractive force of the outer electrons
   • Atomic radius
     • bigger the atomic radius, the smaller the nuclear attraction on the outer electrons
   • electron shielding
     • inner shells of electrons repel outer shell electrons
       • called electron shielding
       • more inner shells, larger the shielding effect and the smaller nuclear attraction