Chapter 1, Problem 38EQ

Nitrobenzene has the skeleton

The number of available valence electrons is: from the phenyl group, ____; from the nitrogen atom, ____; and from each of two oxygen atoms, ____, for a total of ____. Filling in all single bonds and adding the appropriate unshared pairs gives

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The functional group of this structure contains ____ electrons. Therefore, unshared pairs are removed from the nitrogen atom and one of the oxygen atoms; a double bond is added giving

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which has the correct number of electrons. In this structure the nitrogen atom is sharing ____ pairs of electrons. From each shared pair the nitrogen owns ____ electron for a total of ____. Nitrogen is a Group ____ element and would have outer shell electrons in the unbonded, neutral state. Since the nitrogen atom in nitrobenzene has one fewer electron than it would in the neutral state, it has a formal charge of +1 . This is added to the Lewis structure as + giving

Since an electron is negatively charged, a shortage of one electron results in a single positive charge $(+)$ on an atom. Conversely, an excess of one electron results in a single negative charge $\left(2\right)$ on an atom. When an atom in a Lewis structure “owns” two fewer electrons than it would have in the neutral, unbonded state, it is denoted by ++ or +2 and, conversely, $=$ or – 2.