## Step-by-Step Explanation ### **1. What is Formal Charge?** Formal charge is a way to keep track of the electrons assigned to each atom in a molecule. The formula is: \[ \text{Formal charge} = (\text{Valence electrons}) - (\text{Non-bonding electrons}) - \frac{1}{2}(\text{Bonding electrons}) \] --- ### **2. Identify the Circled Atom** The circled atom is **Boron (B)**. --- ### **3. Find Boron's Valence Electrons** - Boron is in group 13 of the periodic table. - **Valence electrons for B = 3** --- ### **4. Count Non-Bonding Electrons on B** - In the Lewis structure, B is bonded to 4 H atoms, and there are **no lone pairs** on B. - **Non-bonding electrons = ** --- ### **5. Count Bonding Electrons Around B** - Each B-H bond contains 2 electrons. - There are **4 bonds** (to H), so: - **Bonding electrons = 4 × 2 = 8** --- ### **6. Calculate the Formal Charge** \[ \text{Formal charge} = 3 - - \frac{8}{2} \] \[ \text{Formal charge} = 3 - - 4 = -1 \] --- ## **Final Answer** \[ \boxed{-1} \] --- ### **Summary Table** | Term | Value | |-----------------------|-------| | Valence electrons | 3 | | Non-bonding electrons | | | Bonding electrons | 8 | | Formal charge | -1 | --- **The formal charge on the circled boron atom is \(\boxed{-1}\).** Let me know if you want to discuss why this is unusual for boron!