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

💡 Solution & Explanation

# Lowest Ionization Potential in a Period **Step 1: Recall ionization potential trend** Ionization potential (IP) increases across a period from left to right due to increasing nuclear charge and decreasing atomic radius. **Step 2: Identify the leftmost element** The element with the lowest IP in any period is the **leftmost element**, which is an **alkali metal (Group 1)**. **Step 3: Explain why** - Alkali metals have only **one valence electron** in their outermost shell - This electron is **furthest from the nucleus** and **least tightly bound** - Minimal nuclear attraction on the outermost electron - Requires the **least energy to remove** **Step 4: Example** In Period 3: Na has the lowest IP (5.14 eV), while Cl has the highest IP (13.0 eV) **Why other options fail:** - **Non-metals** (right side): High nuclear charge pulls electrons strongly → high IP - **Transition metals** (center): Variable oxidation states but still higher than alkali metals - **Halogens** (Group 17): Second highest IP in the period (only noble gases are higher) **Answer: C represents the alkali metal (Group 1 element) at the start of each period.**