Final answer:
Ionic compounds are most likely to form between a metal and a nonmetal due to the transfer of electrons, creating cations and anions that bond together.
Step-by-step explanation:
Atoms that are most likely to form ionic compounds when bonded are a metal and a nonmetal. This occurs because metals tend to lose electrons and form cations, whereas nonmetals tend to gain electrons and form anions. When these oppositely charged ions come together, they form an ionic bond, resulting in the creation of a stable ionic compound. Nonmetals form covalent compounds among themselves by sharing electrons, and two metals do not typically form ionic bonds.
For example, when sodium (a metal) bonds with chlorine (a nonmetal), they form sodium chloride, or table salt. The sodium atom loses an electron to become a sodium ion, while the chlorine atom gains that electron to become a chloride ion. This electron transfer leads to an electrostatic attraction that holds the ions together in a crystalline structure.
In contrast, bonds between two nonmetals typically result in the formation of covalent compounds, not ionic, because these atoms share electrons rather than transferring them. Likewise, bonds between two metals do not form ionic compounds because metals do not readily gain electrons to become anions.