If hydrogen were used as a fuel, it could be burned according to this reaction: H2(g) + 1/2 O2(g) → H2O(g) Which fuel yields more energy per mole?
Ch.9 - Chemical Bonding I: The Lewis Model
Chapter 9, Problem 107a
Draw the Lewis structure for each compound. a. Cl2O7 (no Cl–Cl bond)

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Step 1: Count the total number of valence electrons. Chlorine (Cl) has 7 valence electrons and oxygen (O) has 6 valence electrons. Calculate the total for Cl2O7.
Step 2: Determine the central atom. In Cl2O7, chlorine atoms are typically central, with oxygen atoms surrounding them.
Step 3: Arrange the atoms. Place the two chlorine atoms in the center and connect each to three oxygen atoms, ensuring no Cl-Cl bond is formed.
Step 4: Distribute the electrons. Start by placing single bonds between the Cl and O atoms, then distribute the remaining electrons to satisfy the octet rule for each atom, starting with the outer atoms.
Step 5: Check for formal charges and resonance. Adjust the structure by forming double bonds if necessary to minimize formal charges, ensuring the most stable structure.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Lewis Structures
Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They use dots to represent valence electrons and lines to represent bonds between atoms. Understanding how to draw Lewis structures is essential for visualizing molecular geometry and predicting the behavior of molecules in chemical reactions.
Recommended video:
Guided course
Lewis Dot Structures: Ions
Valence Electrons
Valence electrons are the outermost electrons of an atom and are crucial in determining how atoms bond with each other. The number of valence electrons influences the atom's reactivity and the types of bonds it can form. For example, chlorine has seven valence electrons, which allows it to form bonds with other elements, such as oxygen in Cl2O7.
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Transition Metals Valence Electrons
Molecular Geometry
Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is influenced by the number of bonding pairs and lone pairs of electrons around the central atom, which can affect the molecule's polarity and reactivity. Understanding molecular geometry is important for predicting the properties and behavior of compounds like Cl2O7.
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Molecular Geometry with Two Electron Groups
Related Practice
Textbook Question
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Textbook Question
If hydrogen were used as a fuel, it could be burned according to this reaction: H2(g) + 1/2 O2(g) → H2O(g) Which fuel yields more energy per gram?
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Textbook Question
Calculate ΔHrxn for the combustion of octane (C8H18), a component of gasoline, by using average bond energies and then calculate it using enthalpies of formation from Appendix IIB. What is the percent difference between your results? Which result would you expect to be more accurate?
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Textbook Question
Draw the Lewis structure for each compound. b. H3PO3 (two OH bonds)
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Textbook Question
Draw the Lewis structure for each compound. c. H3AsO4
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Textbook Question
The azide ion, N3-, is a symmetrical ion, all of whose contributing resonance structures have formal charges. Draw three important contributing structures for this ion.
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