What is electron affinity? a. energy change associated with the gaining of several of electrons required to complite the outermost orbital of the atom in the gaseous state b. energy change associated with the gaining of a proton by the atom in the gaseous state c. energy change associated with the gaining of several electrons to complete the outermost sublevel of the atom in the gaseous state d. energy change associated with the gaining of an electron by the atom in the gaseous state