Under which conditions does a complete transfer of electrons occur and what is the result?

• A. When one atom is much more electronegative, the electrons are transferred to form two oppositely charged ions with a full outer shell
• B. When electrons are shared equally
• C. When atoms have identical electronegativity
• D. When both atoms have full outer shells to start with

Answer: (A)

A complete transfer of electrons occurs in ionic bonding, when one atom is much more electronegative and pulls electrons away from the other. This transfer leaves the more electronegative atom with a full outer shell and the other atom with a full outer shell as well, creating oppositely charged ions. The resulting ions are then held together by strong electrostatic attraction, forming an ionic compound.

If electrons are shared equally, as in a nonpolar covalent bond, there isn’t a full transfer—electrons stay in the bond rather than moving completely from one atom to another. If atoms have identical electronegativity, they also tend to share electrons rather than transfer. If both atoms already have full outer shells, there’s no energetic incentive to reconfigure their electrons, so no transfer occurs.