What term measures the attraction an atom has for a shared pair of electrons in a covalent bond?

The term that measures the attraction an atom has for a shared pair of electrons in a covalent bond is electronegativity. This concept reflects how strongly an atom can attract the bonding electrons when it is involved in a covalent bond with another atom.

Electronegativity values are a key element in understanding the behavior of molecules and compounds, particularly how polar or nonpolar the bonds within them are. Atoms with high electronegativity will pull the shared electrons closer to themselves, leading to a polar bond if the other atom involved has a significantly lower electronegativity.

The other options refer to different concepts within chemistry. Ionization energy deals with the energy required to remove an electron from an atom, which does not provide insight into the attraction for shared electrons in a bond. Electron shielding refers to the effect of inner electrons on the effective nuclear charge experienced by outer electrons and does not specifically measure attraction within covalent bonds. Atomic size generally refers to the size of an atom and does not directly relate to its ability to attract shared electrons.