9 The following Lewis structure for OF2 uses how many valence electrons? a) 16 O b) 18 O c) 20 O d) Zero O e) None of the above O 10 Shown here is a Lewis structure for SO3 that expands the octet to minimize formal charges. Select True or False: The formal charge on the sulfur atom is zero. a) True b) false
The correct answer and explanation is:
Question 9: The Number of Valence Electrons in OF₂
Correct Answer: c) 20
Explanation:
To determine the number of valence electrons in the Lewis structure of oxygen difluoride (OF₂), we must first calculate the total number of valence electrons contributed by each atom:
- Oxygen (O) is in Group 16, so it has 6 valence electrons.
- Fluorine (F) is in Group 17, and there are two fluorine atoms, each contributing 7 valence electrons.
Total valence electrons:
( 6 + (7 \times 2) = 6 + 14 = 20 )
Thus, the Lewis structure of OF₂ must account for 20 valence electrons, making the correct answer (c) 20.
Question 10: Formal Charge on Sulfur in SO₃
Correct Answer: a) True
Explanation:
The Lewis structure of sulfur trioxide (SO₃) involves three sulfur-oxygen double bonds. Sulfur, being in Period 3 of the periodic table, can expand its octet to minimize formal charges. To determine the formal charge on sulfur, we use the formula:
[
\text{Formal charge} = (\text{Valence electrons}) – (\text{Non-bonding electrons}) – \frac{(\text{Bonding electrons})}{2}
]
- Sulfur has 6 valence electrons.
- In SO₃, sulfur forms three double bonds with oxygen.
- Sulfur has no lone pairs.
- Sulfur is involved in six bonding pairs (12 electrons total).
Applying the formula:
[
6 – 0 – \frac{12}{2} = 6 – 6 = 0
]
Thus, the formal charge on sulfur is zero, confirming that the statement is true.
Image Generation:
Now, I will generate images of the Lewis structures for OF₂ and SO₃.
Here is the Lewis structure diagram for oxygen difluoride (OF₂) and sulfur trioxide (SO₃). The diagram includes lone pairs, bonding electrons, and formal charges where necessary. Let me know if you need any modifications or further explanations!
