Electronic Configuration of d-Block Elements

The electrical configuration of D block elements is (n-1)d^1-10 ns^1-2. Half-filled orbitals and entirely filled d orbitals are both stable for these elements. The electronic configuration of chromium, which includes half-filled d and s orbitals in its configuration – 3d⁵ 4s¹ – is an example of this.

Copper’s electronic configuration is another example. Copper has a 3d¹⁰ 4s¹ electronic arrangement rather than a 3d⁹ 4s². The relative stability of the entirely filled d orbital can be due to this. In both their ground and general oxidation states, zinc, mercury, cadmium, and copernicium have totally filled orbitals. As a result, these metals aren’t classified as transition elements, while the rest are classified as d block elements.

• Period 4, transition elements’ electronic configuration is (Ar) 4s^1-2 3d^1-10.
• Period 5, transition elements’ electronic configuration is (Kr) 5s^1-2 4d^1-10.
• Period 6, transition elements’ electronic configuration is (Xe) 4s^1-2 3d^1-10.

According to the Aufbau principle and Hund’s rule of multiplicity, electrons are added to the 3d subshell from left to right along the period.

All of the series have anomalies, which can be explained by the following considerations.

1. The distance between the ns and (n-1) d orbitals in terms of energy.
2. Half-full orbitals are more stable than partially filled orbitals.
3. Pairing energy for electrons in s-orbitals.

Chromium has a 4s¹ 3d⁵ electron configuration rather than a 4s² 3d⁴ electron configuration, while copper has a 4s¹ 3d¹⁰ electron configuration rather than a 4s² 3d⁹. The stability of half-full orbitals relative to partly filled orbitals explains these oddities in the first transition series.

From niobium onwards, electron presence in d orbitals appears to be preferred over electron sharing in s orbitals in the second series of transition metals. The electron can choose between sharing in the s orbital or being stimulated to the d orbital from the available s and d orbitals. Obviously, the choice is determined by the amount of repulsive energy overcome during sharing and the energy difference between the s and d-orbitals.

Because the s and d-orbitals have about the same energy in the second series, electrons choose to occupy the d-orbital. As a result, s-orbital has only one electron in niobium. Transition metals of the third series, on the other hand, have a higher number of paired s configurations, even at the expense of half-filled orbitals. This series follows the filling of 4f orbitals and the lanthanide contraction that follows.

Because of the smaller size, the ‘f’ electron provides a lot of shielding for the d orbitals. The energy gap between the s and 5d orbitals is increased as a result of the shielding, and the pairing energy is less than the excitation energy. Despite the stability provided by half-filled orbitals, tungsten does not allow for electron excitation.

Check: Electron Configuration

Electronic Configuration of the d-block elements are those that can be found in the contemporary periodic table from the third to the twelfth groups. These elements’ valence electrons are located in the d orbital. d-block elements are sometimes known as transition elements or transition metals. The 3d, 4d, and 5d orbitals are represented by the first three rows of the d block elements, respectively.