The primary difference between Ionization energy and electron affinity is that Ionization energy is the energy required to remove an electron from a neutral atom, while electron affinity is the energy released when a neutral atom gains an electron.
What is Ionization Energy?
Ionization energy, also known as ionization potential, is the amount of energy required to remove an electron from an atom or ion in its gaseous state. It’s a measure of the strength of the attraction between the electron and the nucleus. Higher ionization energy indicates a stronger bond between the electron and the nucleus.
What is Electron Affinity?
Electron affinity is the energy change that occurs when an atom in its gaseous state gains an electron to form a negatively charged ion (anion). It represents the tendency of an atom to accept an additional electron and is a measure of how strongly an atom attracts an extra electron.
Ionization Energy Vs Electron Affinity
The basic difference between Ionization energy and electron affinity is given below:
| Property | Ionization Energy | Energy is released when an electron is added to a neutral atom to form an anion. |
| Definition | Some anomalies in the trend are due to fully filled or half-filled subshells. | Energy is required to remove an electron from a neutral atom to form a cation. |
| Units | Usually measured in electron volts (eV) or kilojoules per mole (kJ/mol). | Measured in electron volts (eV) or kilojoules per mole (kJ/mol). |
| Sign | Positive value (endothermic process) as energy is required to remove an electron. | Negative value (exothermic process) as energy is released when an electron is added. |
| Trend | Generally increases across a period (left to right) and decreases down a group (top to bottom) in the periodic table. | Generally increases across a period (left to right) and decreases down a group (top to bottom) in the periodic table. |
| Exceptions | Some anomalies in the trend are due to fully-filled or half-filled subshells. | Trends can vary based on the specific elements and their electronic configurations. |
| Application | Used to predict reactivity, ionization tendencies, and chemical behavior. | Used to predict the stability of anions in chemical reactions. |