Ionization Energy Trends in Periodic Table

First Ionization Energy Trend

• Increases: Across a period from left to right, the first ionization energy generally increases.
• Reason: Due to increasing nuclear charge, effective nuclear charge increases, pulling electrons closer to the nucleus, requiring more energy to remove them.
• Atomic radius decreases: As you move across a period, atomic radius decreases due to increasing effective nuclear charge.

First Ionization Energy Down a Group

• Decreases: Down a group, the first ionization energy generally decreases.
• Reason: Electrons are further from the nucleus, shielded by inner electron shells, making them easier to remove.
• Atomic radius increases: Down a group, the atomic radius increases, resulting in weaker attraction to the nucleus, decreasing ionization energy.

Non-Linear Trend in Ionization Energy

• Electron Configuration: The graph of ionization energy versus atomic number across a period shows a non-linear trend due to electron configurations.
• Valence Shell Occupancy: Half-filled and fully-filled subshells are more stable than partially filled ones.
• Exceptional Increases: Elements with half-filled or fully-filled valence shells exhibit higher ionization energies compared to their neighbors.

Greatest Ionization Energy Difference

• Elements with Large Difference: Elements located at the far left and far right of the periodic table, such as alkali metals and halogens, typically have the greatest difference in ionization energies.
• Example: Lithium (Li) and fluorine (F), for instance, exhibit a significant difference in their ionization energies.

Exceptions in Ionization Energy Trends

• Electron Configuration Effects: The periodic trends of ionization energy can be influenced by electron configuration.
• Small Deviations: Small deviations from the general trends may arise from these electronic configurations.
• Example: The ionization energy of nitrogen (N) is higher than oxygen (O), despite oxygen being located to the right of nitrogen.
• Explanation: This is due to the half-filled p subshell in nitrogen's electron configuration, making it more stable and requiring more energy to remove an electron.

This quiz explores the trends in first ionization energy as you move across a period from left to right in the periodic table. Understand key concepts relating to atomic structure and element properties as you test your knowledge on this fundamental chemistry topic.