Which of the following is a characteristic of transition metals?

Transition metals are known for their complex chemistry, which includes the ability to form a variety of compounds and coordination complexes. One of the defining characteristics of transition metals is their variable coordination numbers. This means they can bond with different numbers of ligands, leading to a diversity of complex structures. For example, they can form octahedral complexes with six ligands, tetrahedral complexes with four, or square planar complexes with four as well. This versatility arises from their unique electronic configurations and the presence of d-orbitals, which allow for different arrangements of electrons when bonding with other atoms.

The capacity to exhibit variable coordination numbers is significant because it enables transition metals to participate in a wide range of chemical reactions and processes, making them essential in fields such as catalysis, biological systems, and materials science. This variability in bonding and coordination is a key factor in the rich chemistry associated with these elements, contributing to their colorful compounds and varied oxidation states.