Question

question 5 (2 points)
what is the formal charge on the atom designated #3?
+1
-2
-1
+2
0

Explanation:

Step1: Recall the formula for formal charge

The formula for formal charge is \(FC = V - N - \frac{B}{2}\), where \(V\) is the number of valence electrons of the atom in the free state, \(N\) is the number of non - bonding electrons, and \(B\) is the number of bonding electrons.
For oxygen, \(V = 6\).

Step2: Determine \(N\) and \(B\) for atom #3

For atom #3: \(N = 6\) (non - bonding electrons) and \(B = 2\) (bonding electrons, since it has a double bond which has 2 pairs of bonding electrons, so \(B = 4\) is wrong. Wait, no, in the formula \(B\) is the total number of bonding electrons. A double bond has 4 bonding electrons. But wait, no, the formula is \(FC=V - N-\frac{B}{2}\). For atom #3 (oxygen):
\(V = 6\), \(N = 6\) (lone pairs: 3 lone pairs, \(3\times2=6\)), \(B = 2\) (in a double bond, each bond has 2 electrons, but in terms of the formula, for a double - bonded oxygen in \(O_3\) (ozone - like structure assumed here), the bonding electrons \(B = 4\) (since a double bond has 4 electrons involved in bonding). Wait, no, correction:
The formula is \(FC=V-(N + \frac{B}{2})\). For atom #3 (oxygen):
\(V = 6\) (valence electrons of O), \(N = 6\) (non - bonding electrons: 3 lone pairs), \(B = 2\) (because in terms of the formula \(FC = V-(N+\frac{B}{2})\), for a double - bonded oxygen (assuming the structure is similar to \(O_3\)):
\(FC=6-(6 + \frac{2}{2})\)
\(=6-(6 + 1)\)
\(=6 - 7=- 1\)

Answer:

-1