How do the electron configurations of transition metals differ from main group elements?

Transition metals have electron configurations that fill the d-orbitals, unlike main group elements that fill s and p orbitals.

Transition metals are found in the d-block of the periodic table, which means their electron configurations end in the d-orbitals. This is in contrast to main group elements, also known as representative elements, which are found in the s and p blocks of the periodic table and have electron configurations that end in the s or p orbitals.

The electron configuration of an atom describes the distribution of electrons in its atomic orbitals. For main group elements, the electron configuration follows the pattern of filling the 1s orbital first, then 2s, 2p, 3s, 3p, 4s, and so on. This pattern is based on the Aufbau principle, which states that electrons occupy the lowest energy levels first.

However, transition metals do not strictly follow this pattern. After the 4s orbital is filled, electrons begin to fill the 3d orbital. This is because for transition metals, the 3d orbital is of a similar energy level to the 4s, and can sometimes be of lower energy depending on the specific element. This results in a unique electron configuration where the outermost electrons are found in both the 4s and 3d orbitals.

Another key difference is that transition metals often have partially filled d-orbitals. This is unlike main group elements where the s and p orbitals are either completely filled or empty in their ground state. The partially filled d-orbitals of transition metals contribute to their unique properties, such as their ability to form complex ions, their variable oxidation states, and their magnetic properties.

In summary, the electron configurations of transition metals differ from main group elements in that they fill the d-orbitals, often have partially filled d-orbitals, and do not strictly follow the Aufbau principle. These differences in electron configuration result in the unique chemical and physical properties of transition metals.