Ch.7 - Covalent Bonding and Electron-Dot Structures
Indietro
- The graph shows how potential energy changes as a function of the distance between two atoms. (LO 7.2)
Problema 1
What is the length of the bond between the two atoms? (a) 3.4 angstroms (b) 3.8 angstroms (c) 6.0 angstroms (d) 8.0 angstroms
- Which molecule has the shortest carbon–oxygen bond? (LO 7.3, 7.9) (a) CH3OH (b) CO (c) CO2 (d) HCOOH
Problema 2
- The compounds below are paired with a type of bonding. Which type of bonding is incorrectly classified? (LO 7.5) (a) Rb2O (polar covalent) (b) SO2 (polar covalent) (c) O3 (nonpolar covalent) (d) KBr (ionic) (e) HF (polar covalent)
Problema 3
- Which compound is a solid at room temperature? (LO 7.8) (a) H2O (b) Na2S (c) SO3 (d) Cl2
Problema 5
Problema 10
Which of the following pairs represent resonance structures? (LO 7.13) (a)(b)(c)
Problema 11
The structure for the DNA base cytosine is shown.
Which of the following is not a resonance structure of cytosine? (LO 7.13) (a)
(b)
(c)
(d)
- What is the best prediction for the carbon–oxygen bond length in the carbonate anion, CO3 2-? (LO 7.14) Data for average carbon-oxygen bond lengths: (a) 143 pm (b) 132 pm (c) 121 pm (d) 118 pm
Problema 12
- Which is the best electron-dot structure for the thiosulfate ion (S2O3 2-) based on the rules of formal charge? (LO 7.16) (a) (b) (c) (d)
Problema 14
Problema 15
Use formal charge to select which resonance structure makes the largest contribution to the resonance hybrid. (LO 7.16) (a) Structure I (b) Structure II (c) Structure III (d) All structures are equivalent and make the same contri-bution to the resonance hybrid. (I)
(II)
(III)
- Which of the following alkali metal halides has the largest lat-tice energy? Explain. (a) (b) (c)
Problema 29
- The following diagram shows the potential energy of two atoms as a function of internuclear distance. Match the descriptions with the indicated letter on the plot. (a) Repulsive forces are high between the two atoms. (b) The two atoms neither exert attractive nor repulsive forces on one another. (c) The attractive forces between atoms are maximized, resulting in the lowest energy state. (d) Attractive forces between atoms are present but are not at maximum strength.
Problema 31
- The following diagram shows the potential energy of two atoms as a function of internuclear distance. Which bond is the strongest? Which bond is the longest?
Problema 32
Problema 33
Two electrostatic potential maps are shown, one of methyl-lithium (CH3Li) and the other of chloromethane (CH3Cl). Based on their polarity patterns, which do you think is which? (a)
(b)
Problema 34
Electrostatic potential maps of acetaldehyde (C2H4), ethane (C2H6), ethanol (C2H6O), and fluorethane (C2H5F) are shown. Which do you think is which? (a)
(b)
(c)
(d)
- Characterize bonds between the two atoms as covalent or ionic. (a) Cl and F (b) Rb and F (c) Na and S (d) N and S
Problema 35
- The following ball-and-stick molecular model is a representation of thalidomide, a drug that causes birth defects when taken by expectant mothers but is valuable for its use against leprosy. The lines indicate only the connections between atoms, not whether the bonds are single, double, or triple. (Red = O, gray = C, blue = N, ivory = H). Give the formula of thalidomide, and indicate the positions of multiple bonds and lone pairs.
Problema 37
- Match the following descriptions with the type of bond (ionic, nonpolar covalent, covalent). (a) One or more electrons are transferred from a metal to a nonmetal atom.
Problema 40
- Why do two atoms come together to form a covalent bond? (a) Attractive forces between the positively charged nuclei and the electrons in both atoms occur when the atoms are close together. (b) Repulsive forces between protons in the nuclei of the two atoms are minimized when the atoms are close together. (c) Repulsive forces between electrons in the two atoms are minimized when the atoms are close together.
Problema 41
- Explain the difference in the bond dissociation energies for the following bonds: (C-F, 450 kJ/mol), (N-F, 270 kJ/mol), (O-F, 180 kJ/mol), (F-F, 159 kJ/mol).
Problema 42
Problema 46
What general trends in electronegativity occur in the periodic table?
Problema 47
Predict the electronegativity of the undiscovered element with Z = 119.
- Order the following elements according to increasing electronegativity: Li, Br, Pb, K, Mg, C.
Problema 48
- Order the following elements according to decreasing electronegativity: C, Ca, Cs, Cl, Cu.
Problema 49
- Which of the following substances contain bonds that are largely ionic? (a) HF (b) HI (c) PdCl2 (d) BBr3 (e) NaOH (f) CH3Li
Problema 50
- Show the direction of polarity for each of the bonds in Problem 7.51 using the notation. (b) Si-Li or Si-Cl
Problema 52
- Which of the substances CdBr2, P4, BrF3, MgO, NF3, BaCl2, POCl3, and LiBr contain bonds that are: (b) nonpolar covalent?
Problema 54
- Which of the substances S8, CaCl2, SOCl2, NaF, CBr4, BrCl, LiF, and AsH3 contain bonds that are: (a) largely ionic? (b) nonpolar covalent? (c) polar covalent?
Problema 55
- Order the following compounds according to the increasing ionic character of their bonds: CCl4, BaCl2, TiCl3, ClO2.
Problema 56
- Using only the elements P, Br, and Mg, give formulas for the following. (b) A molecular compound with polar covalent bonds that obeys the octet rule and has no formal charges
Problema 58
Problema 58a
Using only the elements P, Br, and Mg, give formulas for the following. (a) An ionic compound