5.3 Ionization Potential of Transition Elements

  Periodic Table

• In transition elements, the value of ionization potential has very little increase on going from left to right in a period because the outermost orbit remains the same but electrons get filled up in the $(n-1)d$ orbitals resulting in very little increase in the values of ionization potential.
• In transition element series, the first ionization potential normally increases with increase in atomic number on going from left to right, but this periodicity is not uniform. The value of ionization potential of transition elements depends on the following two important factor,
• The value of ionization potential increases with increase in effective nuclear charge.
• The value of ionization potential decreases with increase in shielding effect, when the number of electrons increases in $(n-1)d$ orbitals.
• In the first transition element series, the first ionization potential normally increases on going from left to right from $Sc$ to $Cr$ because shielding effect is much weaker in comparison to effective nuclear charge. The value of first ionization potential of $Fe, Co \:and \:Ni$ remains constant, because shielding effect and effective nuclear charge balance one another. The value of ionization potential shows slight increase from $Cu \:to\: Zn$ because they have fully filled s & $d$ orbitals. The value of first ionization potential of Mn is maximum because it has maximum stability due to fully filled $s$ and half filled orbitals.

• Ionization Potential of Inner Transition Elements