Final answer:
Electronegativity values indicate how strongly atoms attract electrons, helping to determine bond type. Carbon and nitrogen do not readily form ions due to balance in energy considerations, while sodium and chlorine do because of their tendencies to achieve stable electronic configurations. Ionic bonds are not necessarily weaker than covalent bonds; they're strong due to electrostatic attraction but can appear weaker under certain conditions.
Step-by-step explanation:
Electronegativity values are helpful in determining if a bond is ionic, polar covalent, or nonpolar covalent because they provide a relative measure of how strongly an atom attracts electrons in a bond. The larger the difference in electronegativity between two bonding atoms, the more polarized the electron distribution and, consequently, the larger the partial charges of the atoms. In general, when the electronegativity difference is more than 1.8, the bond is typically ionic, with electrons being transferred rather than shared. For a smaller difference, the bond is covalent, but it may be polar covalent if the difference is enough to create a partial charge on each atom.At two different examples are atoms like carbon and nitrogen that tend not to form ions due to having a balance between the energy needed to remove electrons (ionization energy) and the energy advantage of having a full valence shell. On the other hand, sodium and chlorine readily form ions because sodium can easily lose one electron to attain a full outer shell, while chlorine can gain one electron to complete its valence shell, resulting in a stable electronic configuration. It is a misconception that ionic bonds are usually weaker than covalent bonds. In reality, ionic bonds can be very strong due to the electrostatic attraction between oppositely charged ions; however, when comparing the strength in different conditions, such as in the gas phase, ionic bonds may seem weaker because they are more brittle and can be disrupted by the polar nature of solvents like water.