Hw7-Int-GenBond-PDF - Exercise Set 7 GENERAL CONCEPTS of...

Info icon This preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Exercise Set 7 GENERAL CONCEPTS of CHEMICAL BONDING CHM 2045 HwB~GfiGenBondmd 4. 5. Common Monoatomic Ions identify the following monoatomic ions as having noble gas (1 $2 or nsznpa) , pseudo-noble gas (nd‘o) , or ns2 (n—1)dm configurations : a) Al3+ b) Ga3+ c) Sc” d) N3" e) Pb2+ f) K“ 9) Ba” h) Cu+ i) can j) Tr k) Bi“ l) 32- m) Br“ n) H' o) 02- p) Be“ First write the ground state electron configuration of each atombelow. Next determine the number of electron(s) that might be added or removed to yield reasonably stable electron configuration(s) for monoatomic cation(s) or anion(s) of that atom. Then write the ion(s) with the correct charge. a) Mg b) Se 0) Ti d) Ag .. e) Cl ’ f) P Q) Li h) Na i) Sn j) F - k) Ca l) in m) o n) Zn 0) Hg p) Cs Predict the charge on the monoatomic ions formed from thefollowing elements in ionic compounds containing these elements: a) As b) Br 0) Ca d) Cs e) | f) Se g) K h) Cu i) Sn j) Fe k) Al l) o m) Co n) Sr 0) Zn p) Hg, q) S r) Cr 5) Mg t) Tl u) Ba v) F w) Pb x) Ni Ionic Bonding M and X in the combinations below represent elements in the third period of the Periodic Table. Identify the elements in each case and write the specific formula for each. a) [M2“][X2’] b) [M*]3[X3‘l C) [Wilma d) [M2*lle3‘lz Determine the charge carried by each monoatomic ion in the following compounds: 3) K28 b) AIN c) AlFa d) Csl e) MgSe f) NaZO g) CaS ‘ h) Mg3N2 i) FeZSS j) Kl k) Li3P l) CuZO 10. 11. 12. Write the chemical formula(s) of the ionic compound(s) formed between each of the following pairs (metal and nonmetal) of elements. Base your ionic formula predictions on the different combinations of monoatomic ions likely for each of the pairs. a) Na,F b) Be,O c) ALS d) Zn, Cl e) K, Se f) Li,N g) Mg,P h) Sn,F i) Ca.H j) Zn, Br k) Tl,O l) K! m) Fe,O n) Hg,Cl 0) Ni, Br .p) Ba,S q) Ga,F r) Cu,O Complete and balance the following equations: - Remember to first write the correct formula of the ionic product, then balance the equation by adjusting only the coefficients. a) K + '2 d b) C5 + P4 "" C) Mg + Se "" d) Al + 02 d e) Zn + Brz f". f) Li + N2 "’ g)Ni+Cl2—+ h)Ca+02_-o i)Ga+F2-o How would the force(and energy) of interaction between positive ion M and negative ion A be affected by the following changes? a) The charge on M is tripled while the charge on A remains the same (no change in distance). b) The charge on A is quadrupled while the charge on M remains the same (no change in distance). c) The charge on M is tripled and the charge on A is quadrupled simultaneously (no change in distance). , d) The distance between M and A is tripled while the charges are unchanged. e) The distance between M and A is decreased by a factor of four with no change in charge. a) Explain why NaCl forms an ionic solid at room temperature rather than gaseous ion (Na*CI‘) pairs. b) Why is it incorrect to speak of the molecular mass or “weight" of NaCl’? The lattice energy , AHml' of NaF is - 916 kJ/mol. The lattice energy of KCl is - 715 kJ/mol. On the basis of this data, which crystal is more stable? Explain. . Explain the following differences in magnitudes (absolute values) of lattice energies: a) CaO > K20 b) MgOK> MgS c) LiF > LiBr d) CuF2 > CuF e) KCl > CsCl , l a) Explain why the lattice enthalpy of magnesium oxide (AHm, = - 3850 kJ/mol) is more negative than that of barium oxide (AHm. = - 3114 kJ/mol). b) Explain why the lattice enthalpy of magnesium oxide (AHm, = - 3850 kJ/mol) is more negative than that of magnesium sulfide (AHm. = - 3405 kJ/mol). Electronegativity 13. What is meant by the electronegativity of an element and what general trends in electronegativity occur in the periodic table? By referring only to the periodic table, arrange the members of each of the following sets in order of increasing electronegativity: a) Be, B, c, Li b) Cl, F, Br,l c) Ca, K, Se, As d) Si, Mg, Al e) Br, 0,0 1‘) S, F, Ca, Se 9) P, F, As, S h) Sr, Cs, Ba, Al i) Li, K, N, Be j) 0, P, S Ionic versus Covalent Bonding 14. When should you expect a compound to contain a Covalent bond? To contain an ionic bond? ’15. Predict which of the following compounds are ionic and which are covalent. a) l2 b) LiCl c) Cl20 d) H28 e) Ban f) 0320 g) BCla h) 802 i) Al203 j) FeO k) NaZS l) PCl3 m) CaCl2 n) cor, o) ClZCO Simple Chemical Nomenclature for Binary Compounds 16. Correctly name each of the compounds below keeping in mind the following guidelines: - In all cases, the less electronegative element is named first followed by the more electronegative element with the "-ide" suffix. . If an ionic compound and the metal has the potential to form more than one positive charge, indicate the specific charge by using parenthetical Roman numerals after the metal name. - If a complex covalent molecule is to be named, use the system of Greek prefixes to inventory the number of atoms of each element in the molecule. a) KF b) CaO c) H28 d) MgCl2 e) FeBr2 f) FeBrs g) HCl h) 802 i) N203 j) N205 k) NasP l) AIZS3 m) Cut) n) CUZO o) 05! p) BeH2 q) SnF2 " r) SnF4 s) ClOz t) Cl207 u) Hl v) H28e w) BaBrZ x) P4010 y) lBr3 2) Nis aa) BrF5 bb) XeF4 cc) [-192er dd) P406! 17. What is the chemical formula of each compound? 3) Potassium iodide b) Calcium oxide c) Hydrogen iodide d) Sodium selenide e) Carbon dioxide f) Phosphorus pentachloride 9) Carbon disulfide h) Magnesium nitride i) Calcium phosphide j) Silver(l) oxide k) Sulfur trioxide l) Tetraphosphorus hexoxide m) Carbon tetrachloride n) Lead(lV) iodide o) Lead(ll) iodide p) Hydrogen teluride q) Zinclodide r) Mercury(l) sulfide 18. 20. s) Mercury(ll) sulfide t) Dichlorine pentoxide u) Iodine heptafluoride ‘ v) Chromium(|ll) oxide w) Nickel(ll) bromide x) Sodium fluoride y) Calcium hydride z) Heptiodine nonoxide aa) Potassium phosphide bb) Cobalt(|l) sulfide cc) ammonia x) Rubidium selenide Covalent Bonding Write Lewis electron structures for the molecules most likely to be formed from the simple combination of nonmetals: . - More than one atom'of each element may be required - After recognizing the number of valence electrons on each atom, deduce the number of single bonds each atom would require in order to share enough electrons to approximate a noble gas configuration. a) H, F b) H, S 6) CI, 0 d) N, Br 6) Br, Br f) Si, Cl 9) P, I h) C, F 3) Br, Cl j) As, H k) Se, Cl I) P, H The following molecules each contain one or more multiple bonds. The sequence of bonding is indicated. Write the correct Lewis structure for each. a) H, N, N, H b) S, C, S c) C, 0 d) S, C, 0 e) Cl, C, C, Cl f) H, c, N g) o, 0, 2H h) N, N ._ i) 2F,C,C, 2F j) c1, N, 0 Why does the "octet rule" or "noble gas rule" not hold for many compounds containing elements in the third period of the periodic table and higher (expanded valence). What exceptions to the octet rule are possible in the second period? Covalent Bond Length 21, 22. 23. Given the following bond distances: Bong 59nd distance, pm Br—Cl 21 3 l-Bl‘ 247 Cl-CI 198 Determine the l-Cl bond distance. Given the follOwing bond distances: Bond Bond distance, gm GO 154 F-F 142 Br—Br 228 H-H 74 Determine the bond lengths of: a) C-F (in CF4) b) Br—F c) H-F d) C-H (in CH4) e) H-Br How are single, double, and triple covalent bonds similar? How do the differ? 24. 25. The nitrogen-nitrogen bond lengths in N2H4 , N2F2 , and N2 are 145 pm, 124 pm, and 110 pm respectively. How can this trend be explained? Consider a series of molecules in which the C atom is bonded to atoms of second period elements: C—O, C-F, C-N, CC, and C-8. Place these bonds in order of increasing bond length. Explain your logic. Bond and Molecular Polarity 26. ”27. ' 28. 29. 30. 31. How does the electronegativity difference between the atoms in a covalent bond affect the olarit of th bond? Arrange the following individual bonds in order of increasing polarity using electronegativities of atoms. Indicate the partial charges for the bonds using the symbols 5+ and 6- . a) H—F , H-C , H-H b) H—Se , P-Cl, N-CI c) P-S, Si—Cl, Al—Cl d) CI—l, P-P, C-N, O-H e) Si-O, C-Br, As-Br f) C—N, C—H, C-Br, 8-0 In each pair of bonds, indicate the more polarbond by using an arrow (-v) to show the polarity (positive to negative) in each bond. The arrow may represent the bond moment and increases in length in proportion to the polarity of the bond. a) C-0 and C-N b) P-0 and P-S c) P-H and P—N d) 8-H and Bi Each of the following molecules contain only one covalent bond. Therefore the polarity of each individual bond determines the polarity of the molecule. List the following molecules in order of increasing molecular polarity, i.e., list in order of increasing molecular dipole moment, u . a) l-Cl b) Br-Cl c) Cl-Cl d) Br-F e) CI-F Water, H20 , is a bent molecule with an angle of 105° between the two 0-H bonds. Which end of one of the OH bonds in water carries a partial positive charge and which end carries a partial negative charge? Sketch the H20 molecule and indicate the net center of positive charge and the net center of negative charge within the molecule. a) How is the polarity of a covalent bond related to the polarity of a mglecgle containing the bond? Explain why some molchles that contain polar bonds are not polar. b) Despite the larger electronegativity difference between bonded atoms, BeClZ (g) has no molecular dipole moment (overall a nonpolar molecule), whereas SClz (9) does possess one. Account for the difference in polarity of these two molecules. c) The PF3 molecule has a dipolemoment of 1.03 D, but BF3 has a dipole moment of zero. How do you explain the difference? " 32. " 33. Dichloroethylene, (ZZHZCl2 , has the following geometries (isomers), each of which is planar and an individual substance: H \ / H H \ / Cl H \ / Cl /C=C \ /C=C\ /C=C \ Cl Cl Cl H H A pure sample of one of these substances is found experimentally to have a dipole moment of zero. Can we determine which of the three substances was measured? Cl Determine which of the following molecules would be gglar, i.e. , would possess a net u > O, and which would be ngngolar. '- The molecular shape of each molecule is given. Sketch this shape. . Draw the bond moments of each polar bond (AEN is helpful) as an arrow (a) over the three dimensional sketch. - Over a‘second (fresh) molecular sketch, draw the correct orientation of the net molecular dipole moment (~) ifthe molecule is polar. If the molecule is nonpolar, write u = 0. a) H20 (angular) b) OFZ (angular) c) C02 (linear) d) 008 (linear) e) BCI3 (trigonal planar) : f) PCI3 (trigonal pyramid) g) CCI4 (tetrahedral) h) HCCI3 (tetrahedral) i) SF6 (octahedral) j) XeF4 (square planar) k) HBr (linear) I) SCl2 (angular) m) 0ze (linear) . n) HCN (linear) Given the observed or experimental molecular dipole moment ( u ), deduce the general shape of each of the following molecules. (the central atom is in bold). a) so2 p=1.63D b) so3 u=0 c) cs2 p=o d) cos p=0.71ZD e) BH3 p=0 ' f) NH3 u=1.47D g) car4 p=0 h) HCBr3u=0.99D i) HZCBrz p= 1.430 j) H28 p= 0.970 R) AsF3 p=2.59D Lewis Electron Structures 35. 36. Use the concept of formal charge to choose the more likely skeleton structure in each of the ‘ following, cases: - a) NNO or NON b) HCN or HNC c) NOBr or ONBr d) NSC‘ or SNC‘ or SCN’ The atmosphere of Titan , the largest moon of Saturn, contains methane (CH4) and traces of ethylene (CZH4), ethane (CZHS), hydrogen cyanide (HCN). propyne (H3CCCH), and diacetylene (HCCCCH). Write the Lewis structures of these molecules. 37. Write acceptable Lewis structures for each of the following molecules or polyatomic ions. Include formal charges where required. If equivalent resonance contributors may be written, do so. ~ a) NF3 b) NH: 0) NH; .d) H3O“ we) 0H t) NH20H -9) N2H4 h) H202 »~i) CH30H ’j) 82 k) FNO T) Csz 'm) CO n) HCN o) HZNCN p) CN‘ q) C02 r) 082 s) H200 1) .HZCCO .u) FNNF .31) N03; w) NO; x) No; y) NO“ 2) CF3' ' aa) BH4' bb) POI),+ cc) SiCl4 dd) CHZN2 ee) so2 m so3 99) so}— m.) 503 - a) 320 m HNCO kk) Oz ' ll) SCIZ mm) SF; on) CZHSCI oo) HCOZH pp) 88 38. The following species do not follow the "octet rule". Write a Lewis electron structure for each. a) SF6 b) BF3 c) PCl5 d) CH; e) Belz r) Xer=2 9) l3' h) PCIG‘ Resonance Theory 39. Given below are two resonance contributors of ozone. What can be said of the relative energy content of these two structures? What implications does this have on the electronic structure and character of the resonance hybrid? OI H o o ;0/ 3.0.24 L... -':o,/ ‘0; 40. Now consider the three Lewis contributors for BeCl2 below. Why is the one in the middle the preferred structure? How might the electronic structure and character of BeClz be understood from the perspective of resonance theory? 9! -I —| N [:él=Be—C:l= ._. :éi-Be—ci: H :éji—Be=ci:] 41. Write resonance descriptions for the following: a) FN02 b) HCO; (C is central atom) c) SCN' 42. Based on their Lewis struCtures, predict the ordering of N-O bond lengths in NC)", NOZ“, NOZ', and N03: 43. a) In the gaseous state, HNO3 molecules have two nitrogen-to-oxygen bond distances of 121 pm and one of 140 pm. Draw plausible Lewis structures that explain this fact. b) The C—F bond length in trifluoromethyl cation, CF3“'. is observed to be 127 pm; much less than the "normal" C-F single bond length of 138 pm observed for CF4. Explain this observation in terms of resonance theory. 44. Which of the following pairs of structures represent resonance forms and which do not? . .1 'i' T 5‘ 7' .. " .. .. n ’I .. .. a) :o=N-—-o: and =o=o=Nz b) H—c-clz-o—H and H-c—g-c—H H H ‘ H H ‘ ., v 3:" ".. -i .. H )0. .. +1 0.: c) =9-CEN1 and =g=c=nz d) H-Q-N< and H-Q-N< .9224 ' \Q. E): .‘co .0 a. u .. " e) =Q- =0: and :N-g: 45. The skeleton form of benzene, CSHG , is given below. Write the resonance forms of benzene? H H H C .H H C H C C C C C C C C H C H H C H H H Valence Shell Electron Pair Repulsion Theory , VSEPR 46. Via valence shell electron pair repulsion (VSEPR) theory. predict the geometric shape of the molecules or ions listed below. . First write the best Lem's structure for each molecule or ion at resonance is a factor. any valid contributor will work). . Then assess the number of o electron pairs about the central atom. Remember that an electron pair counts as a a pair around an atom if it is a single bond pair. a lone pair (nonbonding pair). or is the one a pair present in a multiple bond. . Assume then that all the sigma pairs are located as far apart from one another as possible and derive the resulting geometry. mm W Linear Trigonal planar Tetrahedral Trigonal bipyramid Octahedral - If there is a choice,plaoe the lone pairs in positions where they exert minimal repulsion, and then determine the net molecular geometry by recognizing the shape derived from the relative positions of all of the atomic nuclei. mmhun a) cc:4 b) AsF3 c) lBrz' d) 0102- e) PFS' f) lCl3 9) CF; h) SiF5‘ i) SbF5 ' j) sr=4 k) NH; *1) NHZ‘ m) 3ng n) IE,+ o) BeClz p) BeCL1 ' q) NO; r) SF3" s) CS, t) Hp“ ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern