Problem 79 - Chemistry: An Atoms-Focused Approach

Question

The bismuth in over-the-counter antacids is found as \(\mathrm{BiO}^{+}\) Draw the Lewis structure for the BiO \(^{+}\) cation.

Step-by-Step Solution

Answer

Answer: The Lewis structure for the BiO+ cation consists of a single bond between the central bismuth (Bi) atom and the oxygen (O) atom, with three lone pairs of electrons surrounding the oxygen atom. The formal charge on the oxygen atom is 0, and the formal charge on the bismuth atom is +1.

Step 1: 1. Count valence electrons

To draw the Lewis structure, we first need to count the valence electrons for each atom. Bismuth (Bi) is in the group 15 and has 5 valence electrons, while Oxygen (O) is in group 16 and has 6 valence electrons. Since we have a +1 charge on the cation, we will subtract 1 electron to get the total valence electrons for the cation. Therefore, we have 5 (Bi) + 6 (O) - 1 = 10 valence electrons.

Step 2: 2. Connect the atoms

To connect the atoms, we put the least electronegative atom in the center (Bi), and the more electronegative atom (O) around it. We can use two of our valence electrons to create a single bond between Bi and O. Now, we have 8 valence electrons left.

Step 3: 3. Distribute the remaining valence electrons

We distribute the remaining valence electrons following the octet rule. We place the remaining 8 electrons (4 pairs) around the Oxygen atom (including the lone pair). This will complete the octet for Oxygen. Bismuth, being in the third period, can have an expanded octet, so it is fine with more than 8 electrons around it. In our case, Bismuth has 5 electrons around it.

Step 4: 4. Check the formal charges and stability

To ensure our structure is correct, we need to check the formal charges for both atoms. The formal charge of an atom can be calculated using the formula: Formal Charge = (Valence electrons) - (Non-bonding electrons) - 0.5(Bonding electrons). For Oxygen: Formal Charge (O) = 6 - 6 - 0.5(4) = 0 And for Bismuth: Formal Charge (Bi) = 5 - 0 - 0.5(4) = +1 Since the total formal charge is equal to the charge of the ion (+1), our Lewis structure is correct.

Step 5: 5. Draw the final Lewis structure

Based on the above steps, the final Lewis structure for the BiO\(^{+}\) cation is: O .. | : +1 Bi | : Y