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 elements are: $Li, Na, K, Rb, Cs, Fr$ (excluding hydrogen in modern IUPAC notation) **Step 2: Analyze their electronic configuration** All Group I elements have valence electron configuration: $ns^1$ (one electron in outermost s-orbital) **Step 3: Determine their chemical behavior** - They readily **lose one electron** to form $M^+$ cations - They are highly reactive metals - They show characteristic properties of metallic elements with low ionization energies **Step 4: Official nomenclature** Group I elements (excluding H) are called **Alkali Metals** because: - They react with water to produce alkaline hydroxides: $2Na + 2H_2O \rightarrow 2NaOH + H_2\uparrow$ - Their oxides and hydroxides are strongly basic **Why A is correct:** Group I = **Alkali Metals** — this is the standard IUPAC designation for elements with $ns^1$ valence configuration that form metallic hydroxides and are highly reactive.