ACS Chemistry Practice Exam 2026 – The All-in-One Guide to Exam Success!

When an element has a high electron affinity, it indicates that the element can easily accept electrons to form negative ions. Electron affinity is a measure of the energy change that occurs when an electron is added to a neutral atom in the gas phase. A high electron affinity means that the process is energetically favorable and often releases energy, thereby signifying a strong attraction between the incoming electron and the nucleus of the atom. This tendency to gain electrons is a characteristic feature of nonmetals, which typically form negatively charged ions, also known as anions.

In contrast, the other options don't accurately represent the implication of high electron affinity. The ability to accept protons relates to acidity and proton donation, not electron affinity. The formation of ionic compounds can be a related concept, but merely indicates a tendency to form certain kinds of bonds rather than focusing specifically on electron acceptance. Lastly, high ionization energy refers to the energy needed to remove an electron from an atom, which is conceptually different from adding an electron, further emphasizing that a high electron affinity specifically involves the attraction for electrons rather than repulsion or removal.