What characterizes a complex ion?

A complex ion is characterized by a central metal ion that is bonded to one or more surrounding molecules or ions known as ligands. These ligands can donate pairs of electrons to the metal ion, leading to coordinate covalent bonds. This interaction results in the formation of a complex with distinct properties that are different from those of the individual components.

The central metal ion typically has empty orbitals that can accept electron pairs from the ligands, allowing it to achieve a stable electronic configuration. The complexity of the ion can vary, as it can involve a variety of ligands coordinated to the metal, leading to formations that can include different geometries and charges. This highlights the importance of ligand diversity and coordination chemistry in understanding the behavior and function of complex ions in various chemical contexts.

The other statements do not accurately represent the characteristics of a complex ion. For instance, a complex ion is not merely a single atom surrounded by electrons nor limited to being neutral, as it can carry a charge depending on the nature of the ligands and the metal ion present. Additionally, a complex is not restricted to only two atoms; it can consist of many atoms depending on the number of ligands coordinated to the metal ion.