U5L12 DE EQ - Thu Mar 5 - 8.6 Resonance Structures

Which of the following statements about resonance structures is true?

• Resonance structures show different molecules with the same formula

• In resonance structures, both the atom positions and the electron positions change

• Resonance structures have identical atom positions but different electron arrangements

• A molecule can only have exactly two resonance structures

A student sees the diagram below and says: “The SO₃ molecule must be constantly switching between these three forms.” What is wrong with this statement?

• Nothing is wrong — the molecule does switch between the three forms

• The double-headed arrows mean SO₃ is actually a blend of all three structures, not switching between them

• The double-headed arrows indicate three separate chemical reactions

• Only the first structure is correct; the other two are mistakes

Tags

NGSS.HS-PS1-2

Examine the Lewis structures below. Which molecule or ion would require resonance structures to be properly described?

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Tags

NGSS.HS-PS1-1

The three resonance structures for the carbonate ion (CO₃^2-) are shown below. Why are these considered valid resonance structures of each other?

• They each have a different number of bonds

• The atoms are in the same positions, but the electrons are arranged differently

• The carbon atom moves to a different position in each structure

• Each structure represents a different ion

One Lewis structure for the nitrite ion (NO₂^- ) is shown below. Which of the following is a valid resonance structure of the given structure?

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Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

The three equally dominant resonance structures for the carbonate ion (CO₃^2-) are shown below. What can you predict about the three C—O bond lengths in this ion?

• One bond is shorter than the other two

• All three bonds are equal in length because the actual structure is an average of the resonance structures

• All three bonds are the length of a typical C—O single bond

• The bond lengths change constantly as the ion switches forms

The three resonance structures for SO3 are shown below. Each shows one S=O double bond and two S—O single bonds. What would you predict about the actual S—O bond lengths?

• All three S—O bonds are equal and intermediate in length between a single and double bond

• One bond is always shorter than the other two

• All three bonds are the same length as a typical S—O single bond

• All three bonds are the same length as a typical S=O double bond

In the shorthand representation of benzene shown below, what does the circle inside the hexagon represent?

• The molecule is shaped like a ring with a hole in the center

• All six C—C bonds are equivalent, and the double bonds cannot be assigned to specific edges

• There are six double bonds in the molecule

• The molecule contains an oxygen atom in the center of the ring