Chapter 1, Problem 54EQ

Methanol, $\text{C}{\text{H}}_3-\text{O}-\text{H}$, is a compound in which the formal charge on all the atoms is zero. Consider what results when a proton, $\text{H}+$, becomes bonded to methanol by way of one of the unshared electron pairs on the oxygen atom, i.e.,

This time we use the curved arrow to signify bond making. Now a pair of unshared electrons on oxygen is pushed toward the region between the oxygen atom and the hydrogen ion. It becomes an $\text{O}-\text{H}$ covalent bond.

In the resulting structure the oxygen atom owns one electron from each of ____ shared pairs and two electrons from ____ unshared pair. The total number of electrons that belong to the oxygen atom is ____. Oxygen is a Group ____ element. Since the number of electrons that the oxygen atom owns in this structure is one fewer that it would have in the neutral, unbonded state, the charge on oxygen is ____. The correct Lewis structure for the conjugate acid of methanol is

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Once again charge is conserved. Joining a neutral molecule and a cation must yield a cation. Again the formal charge distribution on the resulting ion is predictable from the arrow. Electrons are pushed away from the oxygen atom, leaving it with a positive charge. Electrons are pushed toward the hydrogen ion, neutralizing its erstwhile positive charg.