The sum of total number of sigma bonds between chromium and oxygen atoms in chromate and dichromate — Chemical Bonding Chemistry Question

💡 Solution & Explanation

**Step 1: Determine the structure of chromate ion (CrO₄²⁻)** Chromate contains one chromium atom bonded to four oxygen atoms. Chromium forms 4 Cr-O sigma bonds (one with each oxygen). - Sigma bonds in chromate = 4 **Step 2: Determine the structure of dichromate ion (Cr₂O₇²⁻)** Dichromate contains two chromium atoms connected by a bridging oxygen atom. Each chromium is bonded to three terminal oxygen atoms, plus the bridging oxygen. For each Cr: - 3 Cr-O sigma bonds (terminal oxygens) - 1 Cr-O sigma bond (bridging oxygen) - Total per Cr = 4 sigma bonds **Step 3: Count total sigma bonds in dichromate** Since there are 2 chromium atoms: - Total Cr-O sigma bonds = 2 × 4 = 8 sigma bonds **Step 4: Calculate the sum** Total sigma bonds between Cr and O in both ions: - Chromate: 4 sigma bonds - Dichromate: 8 sigma bonds - Sum = 4 + 8 = 12 sigma bonds Therefore, the answer is 12.00.