Define ionization energy.

Describe how ionizacion energy impacts ionic bonding.

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. The first or initial ionization energy or Ei of an atom or molecule is the energy required to remove one mole of electrons from one mole of isolated gaseous atoms or ions.

In general, elements having low ionization energies have a more favorable chance to form a cation, thereby having a greater tendency to form ionic bonds. Thus, lower ionization energy of metallic elements favors the formation of an ionic bond.