For which of the following formulas do resonance structures exist? a. SO3^2- b. PBr4^3- c. SCl5^+ d. GaBr3 e. PO4^3- f. IBr4Cl2^+ g. XeOF4 h. I3^- i. NO2 j. TeCl4
The Correct Answer and Explanation is:
Resonance structures occur when a molecule or ion can be represented by two or more valid Lewis structures that differ only in the arrangement of electrons, not in the positions of the atoms. This phenomenon typically arises in species with conjugated systems, delocalized electrons, or formal charges that can be spread over multiple atoms.
Let’s go through each species:
a. SO3^2- (sulfite ion)
Yes, resonance structures exist. The negative charge can be delocalized over the three oxygen atoms, which can each form double bonds with sulfur in different resonance forms. This allows for the spreading of the negative charge across the oxygens.
b. PBr4^3- (phosphorus tetrabromide anion)
Yes, resonance structures exist. The negative charge can be delocalized over the bromines, as phosphorus in this structure would be able to form different bonding arrangements with the bromines in resonance.
c. SCl5^+ (sulfur pentachloride cation)
No, resonance structures do not exist here. The sulfur atom forms five bonds with chlorine, and there is no delocalization of electrons. The positive charge is localized on the sulfur atom.
d. GaBr3 (gallium tribromide)
No, resonance structures do not exist. There is no possibility for delocalization of electrons or multiple valid structures. The bonding is straightforward, with gallium bonding to three bromine atoms.
e. PO4^3- (phosphate ion)
Yes, resonance structures exist. The negative charge can be delocalized over the four oxygen atoms, where each oxygen can participate in double bonding with the phosphorus atom in different resonance forms.
f. IBr4Cl2^+ (iodine tetrabromochloride cation)
No, resonance structures do not exist. The iodine atom is bonded to the halogens in a rigid, fixed manner, and there is no delocalization of electrons. The positive charge is localized on iodine.
g. XeOF4 (xenon oxytetrafluoride)
No, resonance structures do not exist. Xenon typically forms stable bonds, and there is no opportunity for electron delocalization in this structure.
h. I3^- (triiodide ion)
Yes, resonance structures exist. The negative charge and bonding between the iodine atoms can be delocalized over the three iodines, resulting in two possible resonance structures.
i. NO2 (nitrogen dioxide)
Yes, resonance structures exist. The molecule can be represented by two resonance structures where the nitrogen-oxygen bond can alternate between a single and a double bond, with the negative charge being delocalized on the oxygens.
j. TeCl4 (tellurium tetrachloride)
No, resonance structures do not exist. The bonding in TeCl4 is straightforward, with no delocalization of electrons. Tellurium forms four bonds with chlorine atoms.
Summary:
Resonance structures exist for the following:
- SO3^2-
- PBr4^3-
- PO4^3-
- I3^-
- NO2
Resonance structures do not exist for:
- SCl5^+
- GaBr3
- IBr4Cl2^+
- XeOF4
- TeCl4
