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Chapter 8. Basic Concepts of Chemical Bonding
8.1 Chemical Bonds, Lewis Symbols, and the Octet Rule
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What is a chemical bond?
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Describe the types of chemical bonds:
• Ionic bonds
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Covalent bonds
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Metallic bonds
Lewis Symbols
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Which electrons are involved in bonding?.
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Where are they found?
Describe a Lewis symbol and how it is written.
The Octet Rule
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What is the Octet Rule?
8.2 Ionic Bonding
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Consider the reaction between sodium and chlorine:
Na(s) + ½Cl2(g)  NaCl(s)
• Is this reaction endothermic or exothermic?
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ΔHf = –410.9 kJ/mol
What does this imply about the stability of NaCl vs Na and Cl2?
Describe the ionic lattic of NaCl.
Energetics of Ionic Bond Formation
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Separation of the NaCl into sodium and chloride ions is endothermic:
NaCl(s)  Na+(g) + Cl–(g)
ΔH = +788 kJ/mol
• What is the energy required to separate one mole of a solid ionic compound into gaseous ions is called and
what is its symbol?
Basic Concepts of Chemical Bonding 89
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Upon what does the value of lattice energy depend?
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The stability of the ionic compound comes from the attraction between ions of unlike charge.
What is Coulomb’s equation:
Calculation of Lattice Energies: The Born-Haber Cycle
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What is the Born-Haber cycle.
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What pieces of information are needed to calculate the lattice energy?
Electron Configuration of Ions of the Representative Elements
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These are derived from the ______________________________________ of elements with the required number
of electrons added or removed from the most accessible orbital.
Electron configuration of ions can predict stable ion formation: (write the electron configurations for these)
• Na:
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Na+:
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Cl:
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Cl–:
Transition-Metal Ions
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Lattice energies compensate for the loss of up to ________________ electrons.
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Describe how transition metals form ions.
Polyatomic Ions
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Polyatomic ions are formed when there is an overall charge on a compound containing ______________________
bonds.
• Examples: SO42–, NO3–
What are the characteristics of ionic compounds?
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8.3 Covalent Bonding
How is covalent bonding different from ionic bonding?
Lewis Structures
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Formation of covalent bonds can be represented using Lewis symbols.
• What is a Lewis structure?
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How is a pair of shared electrons represented? Multiple pairs? Unshared electrons?
Multiple Bonds
• Describe single, double, and triple bonds and for each type give an example of a molecule that incorporates that
type.
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Generally, how are bond length and bond strength related to whether a bond is single, double or triple?
8.4 Bond Polarity and Electronegativity
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Describe a polar bond.
Electronegativity
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What is electronegativity?
Electronegativity and Bond Polarity
How is electronegativity related to polarity?
Dipole Moments
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What does it mean for a molecule to have a dipole moment?
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How do we represent a molecule with a dipole moment?
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8.5 Drawing Lewis Structures
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List the simple guidelines for drawing Lewis structures:
Formal Charge
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Sometimes it is possible to draw more than one Lewis structure with the octet rule obeyed for all the atoms.
• How do we determine which structure is best?
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How is formal charge determined?
8.6 Resonance Structures
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What are resonance structures?
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How do we indicate resonance?
Resonance in Benzene
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Benzene belongs to an important category of organic molecules called _________________________ compounds.
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Benzene (C6H6) is a _________________________ structure.
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It consists of ____________ carbon atoms in a ________________.
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Each carbon atom is attached to ________ other carbon atoms and ____________ hydrogen atom.
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There are ______________ double and single bonds between the carbon atoms.
Experimentally, how do the CC bonds compare in length?
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Experimentally, benzene is ____________ in shape
How do we draw benzene to emphasize the resonance between the two Lewis structures?. Show it.
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8.7 Exceptions to the Octet Rule
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What are the three classes of exceptions to the octet rule
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8.8 Strengths of Covalent Bonds
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The energy required to break a covalent bond is called the ________________________.
Bond Enthalpies and the Enthalpies of Reactions
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What is the general formula for calculating the enthalpy of a reaction from bond enthalpies?
Bond Enthalpy and Bond Length
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How is bond enthalpy related to bond length?
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