What does it mean when two atoms in a molecule are connected by a “triple bond”? Write the Lewis structure of a molecule containing a triple bond.
> Which of the following molecules contain polar covalent bonds? a. carbon monoxide, CO b. chlorine, Cl2 c. iodine monochloride, ICl d. phosphorus, P4
> On the basis of the electronegativity values given in Fig. 12.3, indicate whether each of the following bonds would be expected to be ionic, covalent, or polar covalent. a. H-O b. O-O c. H-H d. H-Cl
> For each of the following pairs of elements, identify which element would be expected to be more electronegative. It should not be necessary to look at a table of actual electronegativity values. a. Be or Ba b. N or P c. F or Cl
> A(n) chemical bond represents the equal sharing of a pair of electrons between two nuclei.
> Which of the following statements is false concerning bonding? a. Elements with extremely different electronegativities tend to form ionic bonds with each other. b. In an N-O bond, electron density is greater near the O atom. c. An N-O bond is an exam
> Which simple ion would each of the following elements be expected to form? What noble gas has an analogous electron configuration to each of the ions? a. chlorine, Z = 17 b. strontium, Z = 38 c. oxygen, Z = 8 d. rubidium, Z = 37
> In each case, which of the following pairs of bonded elements forms the more polar bond? a. Br-Cl or Br-F b. As-S or As-O c. Pb-C or Pb-Si
> Arrange the following bonds from the least polar to the most polar bond: C-F, Na-F, Ga-F, Si-F
> The geometric arrangement of electron pairs around a given atom is determined principally by the tendency to minimize between the electron pairs.
> In ionic bonding, a. the electrons are shared between the atoms. b. the process of forming an ionic bond is highly endothermic overall. c. the bonding that occurs is usually between two nonmetal atoms. d. a noble gas configuration is formed for each
> Consider the following order: Li < N < F. For which of the following properties does the order show the correct trend? a. size b. electronegativity c. metallic character d. number of unpaired electrons e. More than one of the above properties (a–d)
> A mathematical expression that summarizes Avogadro’s law is .
> The “Chemistry in Focus” segment Taste—It’s the Structure That Counts discusses artificial sweeteners. What are the expected bond angles around the nitrogen atom in aspartame?
> For each of the following molecules or ions, indicate the bond angle expected between the central atom and any two adjacent chlorine atoms. a. Cl2O b. NCl3 c. CCl4 d. C2Cl4
> For each of the following molecules or ions, indicate the bond angle expected between the central atom and any two adjacent hydrogen atoms. a. H2O b. NH3 c. NH4+ d. CH4
> What conditions are considered “standard temperature and pressure” (STP) for gases? Suggest a reason why these particular conditions might have been chosen for STP.
> Explain how the atoms in covalent molecules achieve electron configurations similar to those of the noble gases. How does this differ from the situation in ionic compounds?
> Using the VSEPR theory, predict the molecular structure of each of the following polyatomic ions. a. sulfate ion, SO42- b. phosphate ion, PO43- c. ammonium ion, NH4+
> Using the VSEPR theory, predict the molecular structure of each of the following molecules. a. CBr4 b. PH3 c. OCl2
> Using the VSEPR theory, predict the molecular structure of each of the following molecules. a. NCl3 b. H2Se c. SiCl4
> For the indicated atom in each of the following molecules or ions, give the number and arrangement of the electron pairs around that atom. a. S in SO32- b. S in HSO3- c. S in HS-
> Temperature is a measure of the average of the molecules in a sample of gas.
> Although both the BF3 and NF3 molecules contain the same number of atoms, the BF3 molecule is flat, whereas the NF3 molecule is trigonal pyramidal. Explain.
> What do we assume about the volume of the actual molecules themselves in a sample of gas, compared to the bulk volume of the gas overall? Why?
> Why are all diatomic molecules linear, regardless of the number of valence electron pairs on the atoms involved?
> How is the structure around a given atom related to repulsion between valence electron pairs on the atom?
> At conditions of constant temperature and pressure, the volume of a sample of ideal gas is proportional to the number of moles of gas present.
> For each of the following sets of volume/temperature data, calculate the missing quantity after the change is made. Assume that the pressure and the amount of gas remain the same. a. V = 2.03 L at 24 °C; V = 3.01 L at? °C b. V = 127 mL at 273 K; V =? m
> Why is the geometric structure of a molecule important, especially for biological molecules?
> What is the geometric structure of the SiF4 molecule? How many pairs of valence electrons are present on the silicon atom of SiF4? What are the approximate F-Si-F bond angles in SiF4?
> What is the geometric structure of the boron trifluoride molecule, BF3? How many pairs of valence electrons are present on the boron atom in BF3? What are the approximate F-B-F bond angles in BF3?
> What is the geometric structure of the ammonia molecule? How many pairs of electrons surround the nitrogen atom in NH3? What is the approximate H-N-H bond angle in ammonia?
> What is the geometric structure of the water molecule? How many pairs of valence electrons are there on the oxygen atom in the water molecule? What is the approximate H-O-H bond angle in water?
> Suppose a 125-mL sample of argon is cooled from 450 K to 250 K at constant pressure. What will be the volume of the sample at the lower temperature?
> Suppose 1.25 L of argon is cooled from 291 K to 78 K. What will be the new volume of the argon sample?
> Suppose a 375-mL sample of neon gas at 78 °C is cooled to 22 °C at constant pressure. What will be the new volume of the neon sample?
> A mathematical expression that summarizes Charles’s law is .
> The “Chemistry in Focus” segment Hiding Carbon Dioxide discusses attempts at sequestering (storing) underground CO2 produced at power plants so as to diminish the greenhouse effect. Draw all resonance structures of the CO2 molecule.
> When 50 mL of liquid water at 25 °C is added to 50 mL of ethanol (ethyl alcohol), also at 25 °C, the combined volume of the mixture is considerably less than 100 mL. Give a possible explanation.
> Figure 13.1 shows an experiment that can be used effectively to demonstrate the pressure exerted by the atmosphere. Write an explanation of this experiment to a friend who has not yet taken any science courses to help him understand the concept of atmosp
> The “Chemistry in Focus” segment Broccoli—Miracle Food? discusses the health benefits of eating broccoli and gives a Lewis structure for sulforaphane, a chemical in broccoli. Draw possible resonance structures for sulforaphane.
> Which of the following species exhibits resonance? CH4, OCl2, NO2-, HCN (C is the central atom)
> Suppose a 24.3-mL sample of helium gas at 25 °C and 1.01 atm is heated to 50. °C and compressed to a volume of 15.2 mL. What will be the pressure of the sample?
> Which flask will have the higher pressure: a 5.00-L flask containing 4.15 g of helium at 298 K, or a 10.0-L flask containing 56.2 g of argon at 303 K?
> What pressure exists in a 200-L tank containing 5.0 kg of neon gas at 300. K?
> At what temperature would 4.25 g of oxygen gas, O2, exert a pressure of 784 mm Hg in a 2.51-L container?
> At what temperature will a 1.0-g sample of neon gas exert a pressure of 500. torr in a 5.0-L container?
> Write the simple Lewis structure for each of the following atoms. a. Mg (Z = 12) b. Br (Z = 35) c. S (Z = 16) d. Si (Z = 14)
> Write the simple Lewis structure for each of the following atoms. a. I (Z = 53) b. Al (Z = 13) c. Xe (Z = 54) d. Sr (Z = 38)
> What does it mean when we say that in forming bonds, atoms try to achieve an electron configuration analogous to a noble gas?
> How many electrons are involved when two atoms in a molecule are connected by a “double bond”? Write the Lewis structure of a molecule containing a double bond.
> When elements in the second and third periods occur in compounds, what number of electrons in the valence shell represents the most stable electron arrangement? Why?
> What type of structure must each atom in a compound usually exhibit for the compound to be stable?
> The volume of a sample of ideal gas is proportional to its temperature (K) at constant pressure.
> Why are the valence electrons of an atom the only electrons likely to be involved in bonding to other atoms?
> Figures 13.7 and 13.8 show volume/temperature data for several samples of gases. Why do all the lines seem to extrapolate to the same point at 2273 °C? Explain. High temperature Large volume Low temperature Small volume He He 5 CH, CH, H,
> Pretend that you’re talking to a friend who has not yet taken any science courses, and describe how you would explain the concept of absolute zero to him.
> Under what conditions do real gases behave most ideally?
> What pressure (in atmospheres) is required to compress 1.00 L of gas at 760. mm Hg pressure to a volume of 50.0 mL?
> Why are anions always larger than the atoms from which they are formed?
> The normal boiling point of water is unusually high, compared to the boiling points of H2S, H2Se, and H2Te. Explain this observation in terms of the hydrogen bonding that exists in water, but that does not exist in the other compounds.
> Why are cations always smaller than the atoms from which they are formed?
> If 1.04 g of chlorine gas occupies a volume of 872 mL at a particular temperature and pressure, what volume will 2.08 g of chlorine gas occupy under the same conditions?
> Is the formula we write for an ionic compound the molecular formula or the empirical formula? Why?
> Atoms form ions so as to achieve electron configurations similar to those of the noble gases. For the following pairs of noble gas configurations, give the formulas of two simple ionic compounds that would have comparable electron configurations. a. [He
> Name the noble gas atom that has the same electron configuration as each of the ions in the following compounds. a. barium sulfide, BaS b. strontium fluoride, SrF2 c. magnesium oxide, MgO d. aluminum sulfide, Al2S3
> A sample of gas has a volume of 127 mL in a boiling water bath at 100 °C. Calculate the volume of the sample of gas at 10 °C intervals after the heat source is turned off and the gas sample begins to cool down to the temperature of the laboratory, 20 °C.
> If a 375-mL sample of neon gas is heated from 24 °C to 72 °C at constant pressure, what will be the volume of the sample at the higher temperature?
> What is the expected ground-state electron configuration for Te-2?
> For each of the following numbers of electrons, give the formula of a positive ion that would have that number of electrons, and write the complete electron configuration for each ion. a. 10 electrons b. 2 electrons c. 18 electrons d. 36 electrons
> Which simple ion would each of the following elements be expected to form? Which noble gas has an analogous electron configuration to each of the ions? a. bromine, Z = 35 b. cesium, Z = 55 c. phosphorus, Z = 15 d. sulfur, Z = 16
> The boiling points of the noble gas elements are listed below. Comment on the trend in the boiling points. Why do the boiling points vary in this manner? Не - 272 °С Kr -152.3 °С Ne -245.9 °С Хе —107.1 °С Ar -185.7°С Rn -61.8 °C
> A sample of helium gas with a volume of 29.2 mL at 785 mm Hg is compressed at constant temperature until its volume is 15.1 mL. What will be the new pressure in the sample?
> If the pressure on a 1.04-L sample of gas is doubled at constant temperature, what will be the new volume of the gas?
> Nonmetals form negative ions by (losing/gaining) enough electrons to achieve the electron configuration of the next noble gas.
> The metallic elements lose electrons when reacting, and the resulting positive ions have an electron configuration analogous to the noble gas element.
> A sample of gas in a balloon has an initial temperature of 18 °C and a volume of 1340 L. If the temperature changes to 87 °C and there is no overall change of pressure or amount of gas, what is the new volume of the gas?
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. H-C b. N-O c. N-S d. N-C
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. Si-H b. P-H c. S-H d. Cl-H
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. S-P b. S-F c. S-Cl d. S-Br
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. C-F b. Si-C c. C-O d. B-C
> In each of the following diatomic molecules, which end of the molecule is positive relative to the other end? a. hydrogen fluoride, HF b. chlorine monofluoride, ClF c. iodine monochloride, ICl
> The molar heats of fusion and vaporization for water are 6.02 kJ/mol and 40.6 kJ/mol, respectively, and the specific heat capacity of liquid water is 4.18 J/g °C. What quantity of heat energy is required to melt 25.0 g of ice at 0 °C? What quantity of he
> In each of the following diatomic molecules, which end of the molecule is negative relative to the other end? a. hydrogen chloride, HCl b. carbon monoxide, CO c. bromine monofluoride, BrF
> Why is the presence of a dipole moment in the water molecule so important? What are some properties of water that are determined by its polarity?
> What volume of gas would result if 225 mL of neon gas is compressed from 1.02 atm to 2.99 atm at constant temperature?
> Which bond in each of the following pairs has less ionic character? a. Na-O or Na-N b. K-S or K-P c. Na-Cl or K-Cl d. Na-Cl or Mg-Cl
> In Fig. 13.4, when additional mercury is added to the righthand arm of the J-shaped tube, the volume of the gas trapped above the mercury in the left-hand arm of the J-tube decreases. Explain. Mercury added Gas Gas h Hg Figure 13.4 A J-tube similar
> Pretend that you’re talking to a friend who has not yet taken any science courses, and describe how you would explain Boyle’s law to her.
> Make the indicated pressure conversions. a. 17.3 psi to kilopascals b. 1.15 atm to psi c. 4.25 atm to mm Hg d. 224 psi to atmospheres
> A mathematical expression that summarizes Boyle’s law is .
> The volume of a sample of ideal gas is inversely proportional to the of the gas at constant temperature.
> On the basis of the electronegativity values given in Fig. 12.3, indicate whether each of the following bonds would be expected to be covalent, polar covalent, or ionic. a. S-S b. S-H c. S-K From fig 12.3 21 F Be 3.5 4.0 1.5 20 Ti V Cr Mn L6 16 N
> The molar heat of fusion of benzene is 9.92 kJ/mol. Its molar heat of vaporization is 30.7 kJ/mol. Calculate the heat required to melt 8.25 g of benzene at its normal melting point. Calculate the heat required to vaporize 8.25 g of benzene at its normal
> On the basis of the electronegativity values given in Fig. 12.3, indicate whether each of the following bonds would be expected to be ionic, covalent, or polar covalent. a. O-O b. Al-O c. B-O From fig 12.3 21 F Be 3.5 4.0 1.5 20 Ti V Cr Mn L6 16
> In each of the following groups, which element is the most electronegative? Which is the least electronegative? a. Cs, Ba, At b. Ba, Sr, Ra c. O, Rb, Mg
> The introduction to this chapter says that “we live immersed in a gaseous solution.” What does that mean?
> What factor determines the relative level of polarity of a polar covalent bond?
> A bond between atoms having a (small/large) difference in electronegativity will be ionic.
> Make the indicated pressure conversions. a. 14.9 psi to atmospheres b. 795 torr to atmospheres c. 743 mm Hg to kilopascals d. 99,436 Pa to kilopascals
