Lanthanides and actinides are two series of elements located in the periodic table. They share several similarities, one of which is their oxidation state.

Oxidation State:
The oxidation state of an element refers to the charge it carries when it forms a compound or ion. Lanthanides and actinides both have similar oxidation states due to the presence of f-orbitals in their electronic configuration.

Electronic Configuration:
The electronic configuration of an element describes the arrangement of electrons in its atomic orbitals. Lanthanides have the general electronic configuration [Xe]4f^n5d^06s^2, while actinides have the general electronic configuration [Rn]5f^n6d^07s^2. Both series have partially filled f-orbitals, which can accommodate a maximum of 14 electrons. The presence of these f-orbitals leads to similar chemical properties and the ability to exhibit multiple oxidation states.

Formation of Complexes:
Lanthanides and actinides have a strong tendency to form complexes due to the presence of f-electrons. These f-electrons can participate in bonding and form coordination complexes with ligands. The ability to form complexes is influenced by the oxidation state of the element. Lanthanides generally exhibit a +3 oxidation state, while actinides can exhibit a range of oxidation states, including +3, +4, +5, and +6. The formation of complexes is essential in various fields such as catalysis, medicine, and materials science.

Ionization Energy:
Ionization energy refers to the energy required to remove an electron from an atom or ion. Lanthanides and actinides have relatively high ionization energies due to the strong shielding effect of the f-electrons. The f-electrons shield the outermost electrons from the nuclear charge, making it more difficult to remove them. As a result, lanthanides and actinides tend to form stable, positively charged ions.

In summary, lanthanides and actinides resemble each other in terms of their oxidation state. They both have similar electronic configurations, which allow for the formation of complexes and contribute to their unique chemical properties. Additionally, their high ionization energies make them prone to forming stable, positively charged ions.