Lowest ionization potential in periods is shown by — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

# Lowest Ionization Potential in Periods **Step 1: Understand Ionization Potential** Ionization potential (IP) is the energy required to remove an electron from an atom. Lower IP means easier electron removal. **Step 2: Identify Trends Across a Period** Moving left to right across a period: - Nuclear charge increases - Electrons are added to the same shell - Effective nuclear charge increases - Ionization potential generally **increases** **Step 3: Locate the Lowest IP in a Period** The element at the **beginning (leftmost) of a period** has: - Lowest nuclear charge - Weakest hold on valence electrons - Largest atomic radius - Lowest ionization potential **Step 4: Identify Group 1 Elements** The leftmost elements in each period are **alkali metals (Group 1)**: - Period 1: $H$ (exception, small) - Period 2: $Li$ (lowest IP in period 2) - Period 3: $Na$ (lowest IP in period 3) - And so on... **Conclusion:** **Alkali metals (Group 1 elements, except hydrogen)** show the lowest ionization potential in their respective periods because they have a single valence electron in the outermost shell that is easiest to remove. **Answer: C = Alkali metals / Group 1 elements**