Final answer:
The pair most likely to form an ionic bond is Magnesium (Mg) and Iodine (I), as ionic bonds usually occur between metals and nonmetals and involve the transfer of electrons from the metal to the nonmetal.
Step-by-step explanation:
The pair of elements that is most likely to form an ionic bond is Magnesium (Mg) and Iodine (I). Ionic bonds typically form between metals and nonmetals due to their significant difference in electronegativity. Metals, like magnesium, tend to lose electrons and form positive ions (cations), while nonmetals, like iodine, tend to gain electrons to form negative ions (anions).
In the case of magnesium and iodine, magnesium, being a metal, will lose two electrons to form Mg2+ and iodine, a nonmetal, will gain one electron to form I−. Two iodide ions will balance one magnesium ion, forming the ionic compound magnesium iodide (MgI2).