Write Lewis structures that contribute to the resonance hybrid of \(\mathrm{SO}_{2}\).

Short Answer

Expert verified
The Lewis structures contributing to the resonance hybrid of \(\mathrm{SO}_{2}\) are two structures, each with sulfur at the center, single-bonded to one oxygen and double-bonded to the other, with the double bond location alternating between the two oxygen atoms.

Step by step solution

01

Determine the total number of valence electrons

To draw the Lewis structures of \(\mathrm{SO}_{2}\), first determine the total number of valence electrons available. Sulfur (S) has 6 valence electrons, and each oxygen (O) atom has 6, for a total of \(6 + 2 \times 6 = 18\) valence electrons.
02

Draw the skeletal structure

Arrange the atoms to form a skeletal structure with the least electronegative atom (sulfur) in the center. Connect each oxygen atom to the sulfur atom with a single bond. This accounts for 4 of the 18 valence electrons.
03

Add lone pairs to complete octets

Starting with the outer atoms, add lone pairs of electrons to complete their octets. After accounting for the single bonds, distribute the remaining 14 valence electrons as lone pairs, with each oxygen atom getting 6 additional electrons.
04

Place any remaining electrons on the central atom

After giving each oxygen its full octet, place any remaining electrons on the central sulfur atom. Sulfur now has two lone pairs, for a total of 18 electrons in the structure.
05

Create multiple bond(s) to satisfy the central atom's octet

If the central atom lacks an octet, form double bonds by converting lone pairs from the outer atoms into bonding pairs. For \(\mathrm{SO}_{2}\), form one double bond with sulfur and one oxygen to provide an octet for sulfur. This results in a resonance structure.
06

Draw resonance structures

Since you can form a double bond with either of the two oxygen atoms, there are two possible resonance structures. Draw another structure by forming a double bond with the other oxygen.
07

Assess formal charges

Calculate the formal charges for each atom in both resonance structures to verify the stability. The atoms in the best resonance structure should have the lowest possible formal charges, preferably as close to zero as possible.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Resonance Hybrid
The concept of a resonance hybrid is essential for understanding the molecular structure of certain molecules, where it's not possible to depict the molecule using a single, definitive Lewis structure. For \textbf{SO\(_2\)}, the presence of two possible structures where sulfur forms a double bond with either one of the oxygen atoms leads us to the concept of a resonance hybrid. This concept reflects a more accurate picture of the molecule, illustrating that the actual structure is an average of the resonance forms. The double bond is not fixed between sulfur and one oxygen atom but rather, it's a delocalized bond that shares its electron density across both S-O bonds in reality. Resonance hybrids are widely taught because they provide a more nuanced understanding of electron distribution within a molecule, which impacts reactivity and other chemical properties. The resonance hybrid of \textbf{SO\(_2\)} is important in recognizing the molecule's ability to absorb ultraviolet light, which is relevant for studying atmospheric chemistry and pollution.
Valence Electrons
Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding. For \textbf{SO\(_2\)}, determining the count of valence electrons is the first step in predicting the molecular structure. Sulfur has 6 valence electrons, while each oxygen atom also has 6. In total, for \textbf{SO\(_2\)}, this makes 18 valence electrons available to form bonds and complete octets.Understanding valence electrons is crucial because they dictate how atoms will bond and interact with each other. The total number of valence electrons is used not only in drawing Lewis structures but also in predicting molecular geometry, bond polarity, and reactivity. In educational terms, getting a firm grasp on the concept of valence electrons can significantly simplify many areas of chemistry studies.
Electronegativity
Electronegativity refers to an atom's ability to attract and hold onto electrons. It is a fundamental principle that helps in predicting how atoms will bond with each other. In the case of \textbf{SO\(_2\)}, sulfur is less electronegative than oxygen, hence it becomes the central atom surrounded by the more electronegative oxygen atoms. The difference in electronegativity also has implications for the polarity of the molecule, with the oxygen atoms acquiring a partial negative charge.When drawing Lewis structures, considering electronegativity helps determine the correct placement of atoms and predicts bond polarity. In educational settings, it's important to reinforce the concept of electronegativity not just as abstract numbers on the periodic table but as a practical tool for understanding chemistry.
Lone Pairs
Lone pairs are pairs of valence electrons that are not shared with another atom in a bond and thus, exist alone on an individual atom. In \textbf{SO\(_2\)}, after the skeletal structure is drawn, lone pairs are added to the oxygen atoms to fulfill their octet requirement. Any remaining electrons are considered as lone pairs on the central sulfur atom. Recognizing the role of lone pairs is important for completing Lewis structures and for understanding molecular shapes, since lone pairs can repel bonding pairs and affect molecular geometry. Teaching properly about lone pairs helps students predict the behavior of molecules in different chemical reactions and understand concepts such as VSEPR (Valence Shell Electron Pair Repulsion) theory.
Formal Charge
The formal charge of an atom in a molecule or ion is the difference between the number of valence electrons in the free atom and the number assigned to it in the Lewis structure. It's a tool used to help determine the most likely structure among different Lewis structures or resonance forms. For \textbf{SO\(_2\)}, after drawing the structures, we calculate the formal charges to confirm the most stable resonance structure has formal charges that are as close to zero as possible. In essence, this concept aids in enhancing the stability prediction of various molecular structures. In an educational setting, teaching students how to calculate and interpret formal charges is pivotal in their understanding of structure stability, molecule reactivity, and is often one of the discriminators between possible Lewis structures.
Octet Rule
The octet rule is a chemical rule of thumb that states atoms tend to combine in such a way that they each have an octet of electrons in their valence shells, giving them the same electronic configuration as a noble gas. When applying this rule to \textbf{SO\(_2\)}, we arrange electrons to ensure that the oxygen atoms first comply with the octet rule, since they are more electronegative than sulfur. If there are not enough electrons for the central atom to have an octet, as in the case of sulfur in \textbf{SO\(_2\)}, we modify the bonding structure, such as by creating double bonds, to achieve a complete octet.For educators, it's necessary to point out that while the octet rule is a helpful guideline, there are exceptions to it. These exceptions include molecules with an odd number of electrons, molecules in which one or more atoms possess more or less than eight electrons, and molecules with atoms that have d orbitals. But for \textbf{SO\(_2\)}, it serves as a key concept to arriving at the correct resonance structures.

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