CIE Chemistry Advanced Subsidiary (AS) Level Practice Test

Electronegativity is the tendency of an atom to attract electrons in a covalent bond. It explains why the shared electron pair is drawn toward the more electronegative atom, giving rise to a polar bond and a dipole moment in the molecule. Electron affinity describes the energy change when an isolated atom gains an electron, which is about adding an electron to an atom rather than how electrons are shared in a bond. Bond energy is the energy needed to break a bond, reflecting bond strength rather than how electron density is distributed in the bond. A dipole arises from uneven sharing of electrons due to electronegativity differences, but the underlying property that causes that difference is electronegativity itself.