Final answer:
Ionization energy is the energy needed to remove an electron from a neutral atom, resulting in a cation, while electron affinity is the energy released or absorbed when an electron is added to an atom, forming an anion.
Step-by-step explanation:
The relationship between ionization energy and electron affinity helps explain the energy changes when an electron is added to or removed from a neutral atom. Ionization energy refers to the amount of energy required to remove an electron from a neutral atom, producing a cation. This energy is always positive since energy must be supplied to overcome the electrostatic attraction between the negatively charged electron and the positively charged nucleus.
For example, ionizing hydrogen requires 13.6 electron volts (eV) to move from -13.6 eV to 0, indicating a completely free electron. On the other hand, electron affinity is associated with the change in energy when an electron is added to an atom to form an anion. This change can be exothermic or endothermic, depending on whether energy is released or required in forming the negative ion.