Question

The molecules $S{O_2}$ would be expected to have?
(A) Two identical bonds intermediate between a single and a double bond.
(B) Two single bonds.
(C) Two double bonds.
(D) One single and one double bond.

Answer 1

Sulphur dioxide is the chemical compound with the formula $S{O_2}$ . There are two double bonds between sulfur atoms and oxygen atoms in the $SO$ molecule. Also, a lone pair exists on sulfur atoms and each oxygen atom has two lone pairs in $S{O_2}$ Lewis structure.

Complete answer:
$S{O_2}$ is a bent molecule with ${C_{2V}}$ symmetry point group. A valence bond theory approach considering just $s$ and $p$ orbitals would describe the bonding in terms of resonance between two resonance structures. Sulfur dioxide has a total of $18$ valence electrons: $6$ from the sulfur atom and $6$ from each of the two oxygen atoms. One way of drawing the molecule's Lewis structure has the sulfur atom bonded to the two oxygen atoms double bonds, with two lone pairs of electrons present on each of the oxygens. The remaining two valence electrons are placed on the sulfur atom as a lone pair.
If we break one of the two double bonds and move two bonding electrons on an oxygen atom, we can draw two additional Lewis structures for sulfur dioxide. These structures are called resonance structures and they contribute to the hybrid structure of the molecule. The actual structure of the sulfur dioxide molecule has partial negative charges on the oxygen atoms and a partial positive charge on the sulfur atoms.
So, the correct answer is (A) Two identical bonds intermediate between a single and a double bond.

Note:
The sulfur oxygen bond has a bond order of $1.5$ . There is support for this simple approach that does not invoke d orbital participation. In terms of electron-counting formalism, the sulfur atom has an oxidation state of $+ 4$ and a formal charge of $+ 1$ . Sulfur dioxide is an intermediate in the production of sulfuric acid, being converted to sulfur trioxide, and then to oleum, which is made into sulfuric acid. Sulfur dioxide for this purpose is made when sulfur combines with oxygen.