Final answer:
The maximum number of atoms that can bond to a central atom is defined by the coordination number, which varies depending on the central atom and ligands involved.
Step-by-step explanation:
The maximum number of atoms that can bond to a central atom is referred to as the coordination number. This term is typically used to describe the number of coordinate covalent bonds to the central metal atom in a complex, or the number of closest contacts to an atom in a crystalline form. The coordination sphere includes the central metal atom or ion along with the attached ligands of a complex. The coordination number can vary depending on the size and electronic configuration of the central atom and the ligands that surround it. For example the coordination number for the silver ion in [Ag(NH3)2+)] is two, indicating that two atoms are bonded to the central atom.
In contrast, the coordination number for the cobalt(II) ion in [Co(H2O)6]2+ is six, which means that six atoms can bond to the central cobalt atom. Therefore, the answer to the question What is the maximum number of atoms that can bond to a central atom? is C. Coordination number.