Group I elements of modern periodic table are called — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

# Group I Elements Classification **Step 1: Identify Group I elements** Group I of the modern periodic table consists of: $Li$, $Na$, $K$, $Rb$, $Cs$, $Fr$ (and $H$ in some representations). **Step 2: Examine their electronic configuration** All Group I elements have **one valence electron** in their outermost s-orbital: - $Li$: $1s^2 2s^1$ - $Na$: $[Ne] 3s^1$ - $K$: $[Ar] 4s^1$ **Step 3: Determine their chemical behavior** These elements readily **lose their single valence electron** to form $+1$ cations ($Li^+$, $Na^+$, $K^+$, etc.), achieving stable noble gas configurations. **Step 4: Classification name** Group I elements are called **Alkali Metals** (except hydrogen). --- **Why Option A is correct:** Group I elements are characterized by having one valence electron and exhibiting strong metallic properties with high reactivity. The term "Alkali Metals" specifically refers to their ability to form alkaline (basic) hydroxides like $NaOH$ and $KOH$ when they react with water.