Name: Chemistry
Author: McMurry
ISBN: 9781292336145

Ch.7 - Covalent Bonding and Electron-Dot Structures

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McMurry 8th Edition

Ch.7 - Covalent Bonding and Electron-Dot Structures

Problema 59a

Using only the elements Ca, Cl, and Si, give formulas for the following. (a) An ionic compound

Problema 59b

Using only the elements Ca, Cl, and Si, give formulas for the following. (b) A molecular compound with polar covalent bonds that obeys the octet rule and has no formal charges

Problema 68

Identify the correct electron-dot structure for XeF 5+ (a) (b) (c)

Problema 72

Identify the third-row elements, X, that form the following ions. (a)

Problema 73

Identify the fourth-row elements, X, that form the following compounds. (a)

Problema 74

Acrylonitrile 1C3H3N2 is a molecule that is polymerized to make carpets and fabrics. The connections between atoms are shown.

(d) Identify the shortest bond in the molecule.

Problema 76

Which compound do you expect to have the stronger N-N bond, N2H2 or N2H4? Explain.

Problema 80

Calculate the energy change in kilojoules per mole when lithium atoms lose an electron to bromine atoms to form isolated Li+ and Br-ions. [The Ei for Li1g2 is 520 kJ/mol; the Eea for Br1g2 is -325 kJ/mol.] Will a lithium atom transfer an elec-tron to a bromine atom to form isolated Li+ 1g2 and Br-1g2 ions? Explain.

Problema 83

Ibuprofen 1C13H18O22, marketed under such brand names as Advil and Motrin, is a drug sold over the counter for treatment of pain and inflammation. Complete the structure of ibuprofen by adding hydrogen atoms and lone pairs where needed.

Problema 85b

Draw as many resonance structures as you can for the following nitrogen-containing compounds. Not all will obey the octet rule. Use curved arrows to depict the conversion of one structure into another. (b) NO

Problema 85d

Problema 86

Which of the following pairs of structures represent resonance forms, and which do not? (a)

Problema 87

The estimated lattice energy for CsF21s2 is +2347 kJ/mol. Use the data given in Problem 6.86 to calculate an overall energy change in kilojoules per mole for the formation of CsF21s2 from its elements. Does the overall reaction absorb energy or release it? In light of your answer to Problem 6.86, which compound is more likely to form in the reaction of cesium with fluorine, CsF or CsF2?

Problema 90

Benzene has the following structural formula.

(b) Which statement best describes the carbon–carbon bonds in benzene? (i) Three carbon–carbon bonds are longer and weaker than the other three carbon–carbon bonds. (ii) All six carbon–carbon bonds are identical, and their length and strength are between a double and single bond. (iii) The length of carbon–carbon double bond switches back and forth between the length of a double and a single bond.

Problema 91

Draw three resonance structures for sulfur tetroxide, SO4, whose connections are shown below. (This is a neutral mol-ecule; it is not a sulfate ion.) Assign formal charges to the atoms in each structure.

Problema 92

Some mothballs used when storing clothes are made of naphthalene (C10H8), which has the following incomplete structure.

(a) Add double bonds where needed to draw a complete electron-dot structure.

Problema 93

Four different structures (a), (b), (c), and (d) can be drawn for compounds named dibromobenzene, but only three different compounds actually exist. Explain. (a)

(b)

(c)

(d)

Problema 96

Use the following information plus the data given in Tables 6.2 and 6.3 to calculate the second electron affinity, Eea2, of oxygen. Is the O2-ion stable in the gas phase? Why is it stable in solid MgO? Heat of sublimation for Mg1s2 = +147.7 kJ/mol Bond dissociation energy for O21g2 = +498.4 kJ/mol Eea1 for O1g2 = -141.0 kJ/mol Net energy change for formation of MgO(s) from its elements = -601.7 kJ/mol

Problema 98

Assign formal charges to the atoms in the following structures. Which of the two do you think is the more important contributor to the resonance hybrid?(a)(b)