An element will have lowest ionisation potential when its electronic configuration is — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

# Lowest Ionisation Potential - Electronic Configuration **Key Concept:** Ionization potential (IP) is lowest for elements that most easily lose an electron. ## Step-by-step reasoning: 1. **Elements easiest to ionize** have valence electrons that are: - Furthest from the nucleus (highest period) - In orbitals with minimal nuclear attraction - Least tightly bound 2. **Alkali metals (Group 1)** have the lowest IP because: - Configuration ends in $ns^1$ (single valence electron) - This lone electron experiences minimal shielding effects - Requires least energy to remove 3. **Why other configurations have higher IP:** - $ns^2$ configurations: 2 electrons in outer shell (harder to remove) - $ns^2np^1$ configurations: Penetrating p-orbital, higher IP - Half-filled/filled d or p orbitals: Greater stability, higher IP 4. **Expected answer D:** If option D represents an alkali metal configuration like $[Ne]3s^1$ or similar $ns^1$ pattern in the highest period available, it will have the **lowest ionization potential** among the choices. **Conclusion:** The $ns^1$ configuration (alkali metals) has the lowest ionization potential because the single valence electron is most easily removed.