Which relationship is true regarding electron affinity and proton affinity?

The relationship between electron affinity and proton affinity can be understood through their definitions and the underlying principles of chemical bonding and reactivity. Electron affinity refers to the energy change that occurs when an electron is added to a neutral atom in the gas phase, while proton affinity is the measure of the tendency of a molecule to accept a proton.

Higher proton affinity indicates a stronger ability of a species to accept protons, which often means that the species is less favorable in forming its negative ion counterpart. When a substance has a high proton affinity, it tends to retain its electrons more closely and does not favor the addition of another electron. This results in the correlation where higher proton affinity typically corresponds with lower electron affinity. Essentially, if a species is more inclined to accept protons, it may exhibit a lesser tendency to gain electrons, thus leading to the assertion that higher proton affinity results in lower electron affinity.

Other options do not accurately represent the established relationship between these two affinities. For example, while one might think of a correlation of positive increases in both affinities with atomic number, it is not universally true as trends can vary widely across the periodic table. Similarly, the assertion about electron affinity being indicative of acid character does not accurately reflect the nature of acids and their