Solutions Manual
Organic Chemistry: A Brief Course 13th Edition
By
David J. Hart,
Leslie E. Craine,
Harold Hart,
Christopher M. Hadad
( All Chapters Included - 100% Verified Solutions )
1
, 1
Bonding and Isomerism
Chapter Summary∗
An atom consists of a nucleus surrounded by electrons arranged in orbitals. The electrons
in the outer shell, or the valence electrons, are involved in bonding. Ionic bonds are
formed by electron transfer from an electropositive atom to an electronegative atom.
Atoms with similar electronegativities form covalent bonds by sharing electrons. A single
bond is the sharing of one electron pair between two atoms. A covalent bond has specific
bond length and bond energy.
Carbon, with four valence electrons, mainly forms covalent bonds. It usually forms
four such bonds, and these may be with itself or with other atoms such as hydrogen,
oxygen, nitrogen, chlorine, and sulfur. In pure covalent bonds, electrons are shared equally,
but in polar covalent bonds, the electrons are displaced toward the more electronegative
element. Multiple bonds consist of two or three electron pairs shared between atoms.
Structural (or constitutional) isomers are compounds with the same molecular
formulas but different structural formulas (that is, different arrangements of the atoms in
the molecule). Isomerism is especially important in organic chemistry because of the
capacity of carbon atoms to be arranged in so many different ways: continuous chains,
branched chains, and rings. Structural formulas can be written so that every bond is shown,
or in various abbreviated forms. For example, the formula for n-pentane (n stands for
normal) can be written as:
H H H H H
H C C C C C H or CH3CH2CH2CH2CH3 or
H H H H H
Some atoms, even in covalent compounds, carry a formal charge, defined as the
number of valence electrons in the neutral atom minus the sum of the number of unshared
electrons and half the number of shared electrons. Resonance occurs when we can write
two or more structures for a molecule or ion with the same arrangement of atoms but
different arrangements of the electrons. The correct structure of the molecule or ion is a
resonance hybrid of the contributing structures, which are drawn with a double-headed
arrow (↔) between them. Organic chemists use a curved arrow ( ) to show the movement
of an electron pair.
A sigma (σ) bond is formed between atoms by the overlap of two atomic orbitals
along the line that connects the atoms. Carbon uses sp3-hybridized orbitals to form four
such bonds. These bonds are directed from the carbon nucleus toward the corners of a
tetrahedron. In methane, for example, the carbon is at the center and the four hydrogens
are at the corners of a regular tetrahedron with H–C–H bond angles of 109.5°.
∗ In the chapter summaries, terms whose meanings you should know appear in boldface type.
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
1
2
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
,2 Chapter 1
Carbon compounds can be classified according to their molecular framework as
acyclic (not cyclic), carbocyclic (containing rings of carbon atoms), or heterocyclic
(containing at least one ring atom that is not carbon). They may also be classified according
to functional group (Table 1.6).
Learning Objectives∗
1. Know the meaning of: nucleus, electrons, protons, neutrons, atomic number, atomic
weight, shells, orbitals, valence electrons, valence, kernel.
2. Know the meaning of: electropositive, electronegative, ionic and covalent bonds,
radical, catenation, polar covalent bond, single and multiple bonds, nonbonding or
unshared electron pair, bond length, bond energy.
3. Know the meaning of: molecular formula, structural formula, structural (or
constitutional) isomers, continuous and branched chain, formal charge, resonance,
contributing structures, sigma (σ) bond, sp3-hybrid orbitals, tetrahedral carbon.
4. Know the meaning of: acyclic, carbocyclic, heterocyclic, functional group.
5. Given a periodic table, determine the number of valence electrons of an element and
write its electron-dot formula.
6. Know the meaning of the following symbols:
δ+ δ–
7. Given two elements and a periodic table, tell which element is more electropositive
or electronegative.
8. Given the formula of a compound and a periodic table, classify the compound as
ionic or covalent.
9. Given an abbreviated structural formula of a compound, write its electron-dot
formula.
10. Given a covalent bond, tell whether it is polar. If it is, predict the direction of bond
polarity from the electronegativities of the atoms.
11. Given a molecular formula, draw the structural formulas for all possible structural
isomers.
12. Given a structural formula abbreviated on one line of type, write the complete
structure and clearly show the arrangement of atoms in the molecule.
13. Given a line formula, such as (pentane), write the complete structure and
clearly show the arrangement of atoms in the molecule. Tell how many hydrogens
are attached to each carbon, what the molecular formula is, and what the functional
groups are.
14. Given a simple molecular formula, draw the electron-dot formula and determine
whether each atom in the structure carries a formal charge.
∗ Although the objectives are often worded in the form of imperatives (i.e., determine …,write …, draw …), these
verbs are all to be preceded by the phrase “be able to …”. This phrase has been omitted to avoid repetition.
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
3
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
, Bonding and Isomerism 3
15. Draw the electron-dot formulas that show all important contributors to a resonance
hybrid and show their electronic relationship using curved arrows.
16. Predict the geometry of bonds around an atom, knowing the electron distribution in
the orbitals.
17. Draw in three dimensions, with solid, wedged, and dashed bonds, the tetrahedral
bonding around sp3-hybridized carbon atoms.
18. Distinguish between acyclic, carbocyclic, and heterocyclic structures.
19. Given a series of structural formulas, recognize compounds that belong to the same
class (same functional group).
20. Begin to recognize the important functional groups: alkene, alkyne, alcohol, ether,
aldehyde, ketone, carboxylic acid, ester, amine, nitrile, amide, thiol, and thioether.
ANSWERS TO PROBLEMS
Problems Within the Chapter
1.1 The sodium atom donates its valence electron to the chlorine atom to form the ionic
compound, sodium chloride.
1.2 Elements with fewer than four valence electrons tend to give them up and form
positive ions: Al3+, Li+. Elements with more than four valence electrons tend to gain
electrons to complete the valence shell, becoming negative ions: S2–, O2–.
1.3 Within any horizontal row in the periodic table, the most electropositive element
appears farthest to the left. Na is more electropositive than Al, and C is more
electropositive than N. In a given column in the periodic table, the lower the element,
the more electropositive it is. Si is more electropositive than C.
1.4 In a given column of the periodic table, the higher the element, the more
electronegative it is. F is more electronegative than Cl, and N is more
electronegative than P. Within any horizontal row in the periodic table, the most
electronegative element appears farthest to the right. F is more electronegative than
O.
1.5 As will be explained in Sec. 1.3, carbon is in Group IV and has a half-filled (or half-
empty) valence shell. It is neither strongly electropositive nor strongly
electronegative.
1.6 The unpaired electrons in the fluorine atoms are shared in the fluorine molecule.
F + F F F + heat
fluorine atoms fluorine molecule
1.7 dichloromethane (methylene chloride) trichloromethane (chloroform)
H Cl
H Cl
H C Cl or H C Cl H C Cl or H C Cl
Cl Cl
Cl Cl
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
4
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
Organic Chemistry: A Brief Course 13th Edition
By
David J. Hart,
Leslie E. Craine,
Harold Hart,
Christopher M. Hadad
( All Chapters Included - 100% Verified Solutions )
1
, 1
Bonding and Isomerism
Chapter Summary∗
An atom consists of a nucleus surrounded by electrons arranged in orbitals. The electrons
in the outer shell, or the valence electrons, are involved in bonding. Ionic bonds are
formed by electron transfer from an electropositive atom to an electronegative atom.
Atoms with similar electronegativities form covalent bonds by sharing electrons. A single
bond is the sharing of one electron pair between two atoms. A covalent bond has specific
bond length and bond energy.
Carbon, with four valence electrons, mainly forms covalent bonds. It usually forms
four such bonds, and these may be with itself or with other atoms such as hydrogen,
oxygen, nitrogen, chlorine, and sulfur. In pure covalent bonds, electrons are shared equally,
but in polar covalent bonds, the electrons are displaced toward the more electronegative
element. Multiple bonds consist of two or three electron pairs shared between atoms.
Structural (or constitutional) isomers are compounds with the same molecular
formulas but different structural formulas (that is, different arrangements of the atoms in
the molecule). Isomerism is especially important in organic chemistry because of the
capacity of carbon atoms to be arranged in so many different ways: continuous chains,
branched chains, and rings. Structural formulas can be written so that every bond is shown,
or in various abbreviated forms. For example, the formula for n-pentane (n stands for
normal) can be written as:
H H H H H
H C C C C C H or CH3CH2CH2CH2CH3 or
H H H H H
Some atoms, even in covalent compounds, carry a formal charge, defined as the
number of valence electrons in the neutral atom minus the sum of the number of unshared
electrons and half the number of shared electrons. Resonance occurs when we can write
two or more structures for a molecule or ion with the same arrangement of atoms but
different arrangements of the electrons. The correct structure of the molecule or ion is a
resonance hybrid of the contributing structures, which are drawn with a double-headed
arrow (↔) between them. Organic chemists use a curved arrow ( ) to show the movement
of an electron pair.
A sigma (σ) bond is formed between atoms by the overlap of two atomic orbitals
along the line that connects the atoms. Carbon uses sp3-hybridized orbitals to form four
such bonds. These bonds are directed from the carbon nucleus toward the corners of a
tetrahedron. In methane, for example, the carbon is at the center and the four hydrogens
are at the corners of a regular tetrahedron with H–C–H bond angles of 109.5°.
∗ In the chapter summaries, terms whose meanings you should know appear in boldface type.
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
1
2
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
,2 Chapter 1
Carbon compounds can be classified according to their molecular framework as
acyclic (not cyclic), carbocyclic (containing rings of carbon atoms), or heterocyclic
(containing at least one ring atom that is not carbon). They may also be classified according
to functional group (Table 1.6).
Learning Objectives∗
1. Know the meaning of: nucleus, electrons, protons, neutrons, atomic number, atomic
weight, shells, orbitals, valence electrons, valence, kernel.
2. Know the meaning of: electropositive, electronegative, ionic and covalent bonds,
radical, catenation, polar covalent bond, single and multiple bonds, nonbonding or
unshared electron pair, bond length, bond energy.
3. Know the meaning of: molecular formula, structural formula, structural (or
constitutional) isomers, continuous and branched chain, formal charge, resonance,
contributing structures, sigma (σ) bond, sp3-hybrid orbitals, tetrahedral carbon.
4. Know the meaning of: acyclic, carbocyclic, heterocyclic, functional group.
5. Given a periodic table, determine the number of valence electrons of an element and
write its electron-dot formula.
6. Know the meaning of the following symbols:
δ+ δ–
7. Given two elements and a periodic table, tell which element is more electropositive
or electronegative.
8. Given the formula of a compound and a periodic table, classify the compound as
ionic or covalent.
9. Given an abbreviated structural formula of a compound, write its electron-dot
formula.
10. Given a covalent bond, tell whether it is polar. If it is, predict the direction of bond
polarity from the electronegativities of the atoms.
11. Given a molecular formula, draw the structural formulas for all possible structural
isomers.
12. Given a structural formula abbreviated on one line of type, write the complete
structure and clearly show the arrangement of atoms in the molecule.
13. Given a line formula, such as (pentane), write the complete structure and
clearly show the arrangement of atoms in the molecule. Tell how many hydrogens
are attached to each carbon, what the molecular formula is, and what the functional
groups are.
14. Given a simple molecular formula, draw the electron-dot formula and determine
whether each atom in the structure carries a formal charge.
∗ Although the objectives are often worded in the form of imperatives (i.e., determine …,write …, draw …), these
verbs are all to be preceded by the phrase “be able to …”. This phrase has been omitted to avoid repetition.
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
3
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
, Bonding and Isomerism 3
15. Draw the electron-dot formulas that show all important contributors to a resonance
hybrid and show their electronic relationship using curved arrows.
16. Predict the geometry of bonds around an atom, knowing the electron distribution in
the orbitals.
17. Draw in three dimensions, with solid, wedged, and dashed bonds, the tetrahedral
bonding around sp3-hybridized carbon atoms.
18. Distinguish between acyclic, carbocyclic, and heterocyclic structures.
19. Given a series of structural formulas, recognize compounds that belong to the same
class (same functional group).
20. Begin to recognize the important functional groups: alkene, alkyne, alcohol, ether,
aldehyde, ketone, carboxylic acid, ester, amine, nitrile, amide, thiol, and thioether.
ANSWERS TO PROBLEMS
Problems Within the Chapter
1.1 The sodium atom donates its valence electron to the chlorine atom to form the ionic
compound, sodium chloride.
1.2 Elements with fewer than four valence electrons tend to give them up and form
positive ions: Al3+, Li+. Elements with more than four valence electrons tend to gain
electrons to complete the valence shell, becoming negative ions: S2–, O2–.
1.3 Within any horizontal row in the periodic table, the most electropositive element
appears farthest to the left. Na is more electropositive than Al, and C is more
electropositive than N. In a given column in the periodic table, the lower the element,
the more electropositive it is. Si is more electropositive than C.
1.4 In a given column of the periodic table, the higher the element, the more
electronegative it is. F is more electronegative than Cl, and N is more
electronegative than P. Within any horizontal row in the periodic table, the most
electronegative element appears farthest to the right. F is more electronegative than
O.
1.5 As will be explained in Sec. 1.3, carbon is in Group IV and has a half-filled (or half-
empty) valence shell. It is neither strongly electropositive nor strongly
electronegative.
1.6 The unpaired electrons in the fluorine atoms are shared in the fluorine molecule.
F + F F F + heat
fluorine atoms fluorine molecule
1.7 dichloromethane (methylene chloride) trichloromethane (chloroform)
H Cl
H Cl
H C Cl or H C Cl H C Cl or H C Cl
Cl Cl
Cl Cl
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
4
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
