Ionization Energy vs Electron Affinity

     Ionization energy is the energy needed to remove an electron from a gaseous atom. The first ionization energy is the energy required for removal of the first electron. Electron affinity, on the other hand, can be thought of as the ease with which an electron may be added to an atom, creating an anion. They are essentially opposite in definition, but they both increase as you move and up and right on the periodic table.