Question

Explain the following:

Transition elements tend to be unreactive with increasing atomic number in the series.

Answer 1

1. Transition elements become less reactive as the atomic number increases because the nuclear charge increases, pulling electrons closer and making the atoms more stable.
2. The added electrons enter the (n − 1)d orbitals and cause increased shielding, which balances the increased nuclear charge.
3. This results in atomic radii remaining almost constant after the middle of the series, increasing the stability and reducing reactivity.
4. Additionally, the number of unpaired electrons decreases after the midpoint, weakening metallic bonding and reducing chemical reactivity.

Thus, transition elements tend to be more unreactive with increasing atomic number in the series due to stable electron configurations and effective shielding by d-electrons