INTRO ORGANIC PROBLEMS
FUNCTIONAL GROUPS
1. Classify the following compounds as alkanes, alkenes, alkynes, alcohols, thiols, aldehydes, ketones, amines, amides, carboxylic acids, acid anhydrides, esters, ethers, nitriles or nitro compounds.
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INTRO ORGANIC PROBLEMS
a)
b)
c)
d)
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INTRO ORGANIC PROBLEMS
2. Circle and name all functional groups in the following compounds.
3. Draw generic structures of the following types of compounds. Show all non bonded pairs of electrons.
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INTRO ORGANIC PROBLEMS
a) 1° amine
b) 2° amine
c) 3° amine
d) 1° amide
e) 2° amide
f) 3° amide
g) nitro group
h) nitrile group
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INTRO ORGANIC PROBLEMS
4. Draw generic structures of the following types of compounds. Show all non bonded pairs of electrons.
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INTRO ORGANIC PROBLEMS
a) ether
b) sulfide
c) thiol
d) alcohol
e) phenol
f) alkyl halide
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INTRO ORGANIC PROBLEMS
5. Draw generic structures of the following types of compounds. Show all non bonded pairs of electrons.
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INTRO ORGANIC PROBLEMS
a) peroxide
b) hydroperoxide
c) aldehyde
d) ketone
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INTRO ORGANIC PROBLEMS
6. List 4 examples of synthetic organic compounds:
…………………………………………………………………………………………………………..
7. List 4 examples of natural organic compounds:
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8. Complete the following: Approximately …………. % of fossil fuels consumed is used to make chemical products and approximately ……………….% of fossil fuels consumed is burned as energy.
BONDING
9. How many bonds does carbon always have in its compounds? ……….. . Why can carbon never exceed 4 bonds? …………………………………………………………………………………… .
When can carbon have 3 bonds? ……………………………………………………………………… .
10. The number of bonds a Group A atom forms to become isoelectronic with the nearest noble gas is called its …………………….. .
11. Define ‘isoelectronic’. ……………………………………………………………………..
12. Draw Lewis symbols of phosphorus, oxygen, bromine, silicon and boron atoms.
13. What is the relationship between the Group number and the number of valence electrons for the representative elements? ………………………………………………
14. Define ‘valence’ electrons. …………………………………………………………………………… .
15. Draw the Lewis structure of the hydrides of sulfur, boron, and nitrogen.
FUNCTIONAL GROUPS
16. Identify the type of compound shown in the following structures. Indicate degree of substitution, i.e., 1°, 2°, or 3° where applicable.
17. Circle the functional group(s) in the following structures and state the type.
18. Circle the functional groups and state the types.
19. Write a suitable structure for:
a) two alcohols with the formula C3H8O
b) an ether with the formula C3H8O
c) and aldehyde with the formula C3H6O
d) a cyclic ketone with the formula C4H6O
ELECTRONEGATIVITY
20. Explain in your own words, the meaning of ‘electronegativity’. …………………………………
…………………………………………………………………………………………………………..
21. Without looking at Linus Pauling’s table of electronegativity, rank the atoms in the following clusters in order of increasing EN, where 1 = lowest, 3 = highest. Describe the periodic trends in EN in each case.
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INTRO ORGANIC PROBLEMS
a) F Cl Br
b) N O F
c) Li Na K
d) Be B C
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INTRO ORGANIC PROBLEMS
22. State the value of DEN for pure covalent bonds …………. . Give the formula of 3 pure covalent, non elemental, binary comounds (made from two different atoms). ……………………………………..
23. Write the upper and lower limits of DEN and give one example each of a binary compound for the following:
a) non polar covalent compound
b) polar covalent compound
c) ionic compound
24. Write the symbols meaning ‘partial + charge’ and ‘partial – charge’.
25. The separation of + and – charge creates a ………………….. .
26. Explain the term ‘inductive effect’ as it applies to an OH bond.
27. Use Linus Pauling’s table of EN to calculate the DEN in the bonds of the following compounds and classify each, i.e., polar, non polar, etc.
a) NaBr
b) BeBr2
c) NCl3
28. Write out the ground state electron configuration of the valence shell of each noble gas and explain the importance of these configurations with respect to the chemical behavior of the representative elements.
29. Give the order of decreasing ionization energy for the following, using 1 = lowest, 4 = highest.
a) transition metals, non metals, alkali metals, metalloids
30. Give the name of the theory that means that pairs of electrons move as far apart as possible in a bonded molecule. ………………………………………………………………………………..
BONDING
31. Write out the complete ground state electron configuration of carbon.
32. A single bond is also called a ……………….. bond.
a) A double bond is made of 1 ……………….. bond and 1 …………………. bond.
b) A triple bond is made of 1 ………………… bond and 2 …………………. bonds.
HYBRIDIZATION
33. State the hybridization state of carbon in the following situations:
a) C has four s bonds …………….
b) C has three s bonds and one p bond ……………
c) C has two s bonds and two p bonds. ……………
34. Write the hybridization state of each atom under the conditions shown in the following table:
C
/ N / O / H / Halogenonly s bonds (no p bonds)
one p bond (1 double bond) / ------
two p bonds (2 double or 1 triple) / ------
35. State the hybridization state of the circled atoms in the following compounds:
36. What is true about the hybridization state of H in all of its compounds? ………………………….
37. When are halogens unhybridized? ………………………………………………………………….
38. Give the hybridization state of C in:
a) a methyl cation ………………..
b) a methyl radical ………………..
c) a methyl anion ………………..
39. A compound containing an alternating pattern of single and double (or triple) bonds is said to have ……………………………. unsaturation. When double (or triple) bonds are separated by more than one single bond the compound is said to have ……………………………. unsaturation. When double or triple bonds are adjacent, the compound is said to have ………………………… unsaturation.
CARBOCATION STABILITY
40. Carbocation stability increases as follows; methyl, phenyl, vinyl, 1°, 2° and 3°, with allyl and benzyl having about the same stability as a 2° carbocation. Draw structures of these carbocations in order of increasing stability. (Allyl is slightly less stable and benzyl is slightly more stable than 2° carbocations).
41. Explain the carbocation stability order of 3° > 2° > 1° > methyl. (Hint: there are 2 reasons).
………………………………………………………………………………………………………
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42. List two means by which carbocations are stabilized by adjoining alkyl groups.
………………………………………………………………………………………………………
LEWIS STRUCTURES
43. Draw Lewis structures of phosgene (COCl2), hydrazine (N2H4) and formaldehyde (CH2O).
44. Draw Lewis structures for iodous acid (HIO2), sodium dihydrogen arsentate (NaH2AsO4), and HS-.
45. Draw the Lewis structure of nitromethane (CH3NO2) and calculate the formal charge on the C, the N and both O atoms in the structure.
46. Name and draw the Lewis symbols of the following bonded ions:
a) a cation of bromine ………………………………….
b) a cation of oxygen ………………………………….
c) an anion of carbon …………………………………..
47. List 3 atoms, which after bonding, usually have less than 8 valence electrons. Also give an example of a bonded structure for each.
48. Define ‘hypervalent’ and draw Lewis structures of three compounds in which the central atom is hypervalent.
RESONANCE
49. Draw all possible different resonance structures of a) a benzyl cation, b) a benzyl anion, c) an allyl cation. Show electron movement between structures by pushing electrons with curved arrows.
50. Explain why resonance increases the stability of ions. ………………………………………. ………………………………………………………………………………………………………….
ACIDITY/BASICITY
51. An acid producing a proton (H+ ion) in water is called ………………………………….. acid. Define Arrhenius base and give an example of one. …………………………………………………………. .
………………………………………………………………………………………………………….
52. Define ‘Bronsted acid’. Define Bronsted base and give an example of one that is not an Arrhenius base. …………………………………………………………………………………………………….
………………………………………………………………………………………………………….
53. Acid/base pairs that differ by a proton are called ………………………… acid/base pairs.
54. In the following table, write in the missing conjugate acids and bases and calculate their pK values. Recall pKa + pKb = 14 for all conjugate acid/base pairs. Refer to tables of pK values only as a check.
CH3COOH / 4.7
15.74 / OH-
H2BO3- / 4.8
HAsO4-2 / 11.5
CO3-2 / 3.7
3.1 / NO2-
HSO4- / 2.0
55. Write the formula and give the pKa of the strongest acid that can exist in water …………………… , and the strongest base that can exist in water. ………………………………….. .
56. Explain what is meant by the expression ‘water is a leveling solvent’?
………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………
57. Calculate pKeq and refer to your pKeq graph to determine extent of the forward reaction (% completion) for the following acid/base reactions. Fill in missing formulas as well.
% / pKeq / Acid / Base / Conj. Base / Conj. AcidHBr / NaHCO3 / ® / NaBr / H2CO3
HN3 / KF / ® / KN3
H2SO4 / H2O / ®
58. For what values of pKeq and Keq is a reaction said to ‘go to completion’? ……………….., ………….
59. Answer true or false. (Wrong answers subtracted from correct answers. Do not guess.)
a) An acid will donate a H+ to a base whose conjugate acid is stronger. …………..
b) A base will accept a H+ from an acid whose conjugate base is weaker …………..
60. Define ‘Lewis acid’ and give an example of two that are not Bronsted acids. …………………
……………………………………………………………………………………………………………
61. Define ‘Lewis base’ and give two examples. ……………………………….…………………..
……………………………………………………………………………………………………………
NUCLEOPHILES/ELECTROPHILES
62. The definition of an electrophile is the same as that of a Lewis acid and their periodic trends for binary acids are exactly the same. The definition of a nucleophile is the same as that of a Lewis base but their periodic trends are not exactly the same. Describe the difference. (See page 38 in the notes).
……………………………………………………………………………………………………………
……………………………………………………………………………………………………………
……………………………………………………………………………………………………………
63. Write the formula of a good nucleophile that is also a strong Bronsted base (low pKb) ……………. . Write the formula of a good nucleophile that is a weak Bronsted base (high pKb) ………………. . Write the formula of a good electrophile that is also a strong Bronsted acid (low pKa) ……………….
64. Electrophilic atoms/ions can be recognized in molecules because they are +, or have empty orbitals to receive electron pairs, or are d+ (and have a good leaving group that can leave to make room for a new bond from a nucleophile).
Nucleophilic atoms/ions can be recognized in molecules because they are -, d-, or have loosely held electrons to donate, e.g., non bonded electrons, p electrons in weak p bonds (especially C to C p bonds).
In the following structures, identify all nucleophiles and electrophiles. Where possible indicate if the species is good, fair or poor.
ACIDS/BASES
65. Without looking in pK tables, in each group below, number the compounds in order of increasing acidity, where 1 = least acidic and 4 = most acidic.
a) HBr HF HCl HI
b) OH2 NH3 HF CH4
c) CHF2COOH CH2FCOOH CH3COOH CF3COOH
66. Without looking in tables, approximately how do the acidities of these pairs of acids compare i.e., by what factor do their pKa values differ ?
a) H2SO3 vs. HSO3-, ……………………………….
b) H3AsO4 vs. HAsO4-2 ……………………………..
67. Repeat question 66 for the following series of oxyacids: HIO, HIO2, HIO3, HIO4
……………………………………………………………………………………………………….
68. In each group, circle the atom that is most polarizable.
a) H2O H2S H2Se
b) NH3 PH3 AsH3
c) F- Cl- Br- I-
69. In each group, circle the best leaving group.
a) -I -Br -Cl -F
b) -OH2+ -OH
c) -NH3+ -NH2
70. In each group, circle the one(s) that:
a) cannot be a nucleophile SO4-2 HSO4- H2SO4 Fe+3
b) cannot be an electrophile H+ OH- CH3OH H2O
71. The following mechanism is incorrect. Write the correct mechanism and state what the error was.
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