Final answer:
The best way to predict the type of bond between two atoms—whether it is covalent or ionic—is based on the difference in their electronegativities. Significant differences indicate ionic bonds, while smaller differences lead to covalent bonds. The correct option is a.
Step-by-step explanation:
To predict whether a bond between two atoms is covalent or ionic, you can use electronegativity difference between the atoms. If the difference in electronegativity between the two atoms is significant (usually more than 1.8), the bond tends to be ionic, implying that electrons are completely transferred to the more electronegative atom.
In contrast, a smaller electronegativity difference leads to a covalent bond wherein electrons are shared between atoms. A very small difference, typically less than 0.5, usually indicates a nonpolar covalent bond, especially when the bonded atoms are of the same element.
However, if the bonded atoms are nonmetals but different elements, the bond is likely polar covalent, with the bonding electrons being closer to the more electronegative atom.
Bonds between two nonmetals are typically covalent, while a bond between a metal and a nonmetal is often ionic. The type of bonding also depends on the position of the atoms in the periodic table and their general chemical characteristics. Option a. is the correct one.