1. Chapter 5 Chemical Bonding and States of Matter

2. Chapter Learning Objectives
By the end of the chapter, you will recognize that
Having eight valence electrons is particularly desirable (“the octet rule”).
Atoms form bonds with other atoms to satisfy the octet rule.
The two major types of chemical bonds are ionic and covalent.

3. Chapter Learning Objectives (cont)
Electronegativity is the ability to attract shared electrons.
The type of bond formed between two atoms depends on their difference in electronegativity.
Ionic bonds form between atoms with a large difference in electronegativity (generally a metal and a nonmetal).

4. Chapter Learning Objectives (cont)
Nonpolar covalent bonds form between atoms with little difference in electronegativity (generally two nonmetals).
Polar covalent bonds form between atoms with intermediate difference in electronegativity.
Like dissolves like. That is, polar solutes dissolve in polar solvents.

5. Chapter Learning Objectives (cont)
Intermolecular forces hold the molecules of a material together in different states of matter.
Stronger intermolecular forces lead to higher melting and boiling temperatures.
The relative strengths of intermolecular forces generally follow the trend:
hydrogen bonds > dipole-dipole interactions > London forces

6. Chapter Outline The Octet Rule
The noble gases of Group VIIIA do not typically form compounds with other atoms.
Atoms with eight valence electrons are particularly stable, an observation called the octet rule.
Atoms form bonds with other atoms to achieve a valence octet.
& B.

7. Octet Rule An octet is 8 valence electrons.
is associated with the stability of the noble gases.
He is stable with 2 valence electrons (duet).
valence electrons He
Ne 2,
Ar 2, 8,
Kr 2, 8, 14,

8. Electronic Configuration of Noble Gases

9. Chapter Outline Types of compounds Ionic Covalent
Attractions between oppositely charged particles
Covalent
Atoms share electron pairs.

10. Types of Compounds

11. Chapter Outline Lewis Dot Structures (Review)
The number of valence electrons is equal to the group number for most of the main group elements.
In Lewis dot structures, the chemical symbol represents the nucleus and the core electrons and dots represent the valence electrons.

12. Lewis Dot Structures

13. Chapter Outline Ionic Bonds
Ionic compounds result from the loss of electrons by one atom (usually a metal) and the gain of electrons by another atom (usually a nonmetal).
Ionic bonds arise from the attraction between particles with opposite charges (electrostatic forces); e.g., Na+ Cl-.

14. Ionic and Covalent Bonds
Atoms form octets
to become more stable.
by losing, gaining, or sharing valence electrons.
by forming ionic bonds or covalent bonds. :
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15. Metals Form Positive Ions known as Cations
Metals form positive ions (cations)
by a loss of their valence electrons.
with the electron configuration of the nearest noble gas.
that have fewer electrons than protons.
Group 1A metals  ion 1+
Group 2A metals  ion 2+
Group 3A metals  ion 3+
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16. Formation of a Sodium Ion, Na+
Sodium achieves an octet by losing its one valence
electron.
2, 8, 1
2, 8
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17. Charge of Sodium Ion, Na+
With the loss of its valence electron,
the sodium ion has a +1 charge.
Sodium atom Sodium ion
11p p+
11e e-
2, 8
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18. Learning Check A. The number of valence electrons in aluminum is
1) 1e ) 2e-. 3) 3e-.
B. The change in electrons for octet requires a
1) loss of 3e ) gain of 3e ) a gain of 5e-.
C. The ionic charge of aluminum is
1) ) ) 3+.
D. The symbol for the aluminum ion is
1) Al3+. 2) Al3-. 3) Al+.

19. Solution A. The number of valence electrons in aluminum is 3) 3 e-.
B. The change in electrons for octet requires a
1) loss of 3e-.
C. The ionic charge of aluminum is
3) 3+.
D. The symbol for the aluminum ion is
1) Al3+.

20. Formation of Negative Ions known as Anions
In ionic compounds, nonmetals
achieve an octet arrangement.
gain electrons.
form negatively charged ions with 3-, 2-, or 1- charges.

21. Formation of a Chloride, Cl-
Chlorine achieves an octet by adding an electron to its valence electrons.
2, 8, 7
2, 8, 8
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22. Charge of a Chloride Ion, Cl-
By gaining one electron, the chloride ion has a -1 charge.
Chlorine atom Chloride ion
17p p+
17e e- –
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23. Some Ionic Charges I- Copyright © 2005 by Pearson Education, Inc.
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24. Learning Check A. The number of valence electrons in sulfur is
1) 4e ) 6e ) 8e-.
B. The change in electrons for octet requires a
1) loss of 2e ) gain of 2e-. 3) a gain of 4e-.
C. The ionic charge of sulfur is
1) ) ) 4-.

25. Solution A. The number of valence electrons in sulfur is 2) 6e-.
B. The change in electrons for octet requires a
2) gain of 2e-.
C. The ionic charge of sulfur is
2) 2-.

26. The balance of charges in Al2O3

27. Run the following web animations/movies.
5.1: Formation of Sodium Chloride
5.2: Sodium Metal Reacting with Chlorine Gas
5.3: Ion Formation

28. Ionic Compounds

29. Naming Ionic Compounds with Two Elements
To name a compound that contains two elements,
identify the cation and anion.
name the cation first followed by the name of the anion.

30. Charges of Representative Elements
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31. Names of Some Common Ions
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32. Learning Check Complete the names of the following ions. Ba2+ Al3+ K+
_________ __________ _________
N3 O2 F
_________ __________ _________
P3 S2 Cl

33. Solution Ba2+ Al3+ K+ barium aluminum potassium N3 O2 F
nitride oxide fluoride
P3 S2 Cl
phosphide sulfide chloride

34. Examples of Ionic Compounds with Two Elements
Formula Ions Name
cation anion
NaCl Na+ Cl- sodium chloride
K2S K S2- potassium sulfide
MgO Mg2+ O2- magnesium oxide
CaI2 Ca2+ I- calcium iodide
Al2O3 Al O2- aluminum oxide

35. Learning Check Write the names of the following compounds.
1) CaO ___________
2) KBr ___________
3) Al2O3 ___________
4) MgCl2 ___________

36. Solution Write the names of the following compounds:
1) CaO calcium oxide
2) KBr potassium bromide
3) Al2O3 aluminum oxide
4) MgCl2 magnesium chloride

37. Polyatomic Ions A polyatomic ion is a group of atoms.
has an overall ionic charge.
Some examples of polyatomic ions are
NH4+ ammonium OH− hydroxide
NO3− nitrate NO2− nitrite
CO32− carbonate PO43− phosphate
HCO3− hydrogen carbonate
(bicarbonate)

38. Some Compounds with Polyatomic Ions
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39. Some Names of Polyatomic Ions
The names of common polyatomic anions
end in ate.
NO3− nitrate PO43− phosphate
with one oxygen less end in ite.
NO2− nitrite PO33− phosphite
with hydrogen attached use the prefix hydrogen (or bi).
HCO3− hydrogen carbonate (bicarbonate)
HSO3− hydrogen sulfite (bisulfite)

40. Names and Formulas of Common Polyatomic Ions
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41. Names and Formulas of Common Polyatomic Ions
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42. Naming Compounds with Polyatomic Ions
The positive ion is named first followed by the name of the polyatomic ion.
NaNO3 sodium nitrate
K2SO4 potassium sulfate
Fe(HCO3)3 iron(III) bicarbonate
or iron(III) hydrogen carbonate
(NH4)3PO3 ammonium phosphite

43. Chapter Outline Covalent Bonds
Covalent bonds are formed when two atoms share one or more electron pairs.
A molecule is the fundamental unit of a covalent compound.
When two atoms share one pair of electrons, the result is a single bond.
Two shared pairs of electrons is a double bond; three is a triple bond.

44. Covalent Bonds Covalent bonds form
when atoms share electrons to complete octets.
between two nonmetal atoms.
between nonmetal atoms from Groups 4A(14), 5A(15), 6A(16), and 7A(17).

45. Hydrogen Molecule A hydrogen molecule
is stable with two electrons (helium).
has a shared pair of electrons.

46. Run the following web animations/movies.
5.4: Bond Length and Energy
5.5: Electrostatic Interactions Between Hydrogen Atoms

47. Forming Octets in Molecules
In a fluorine, F2,, molecule, each F atom
shares one electron.
attains an octet.

48. Carbon forms 4 covalent bonds
In a CH4, methane, molecule
a C atom shares 4 electrons to attain an octet.
each H shares 1 electron to become stable like helium.

49. Multiple Bonds In nitrogen molecule, N2,
each N atom shares 3 electrons.
each N attains an octet.
the bond is a multiple bond called a triple bond.
the name is the same as the element.

50. Naming Covalent Compounds
To name covalent compounds
STEP 1: Name the first nonmetal as an element.
STEP 2: Name the second nonmetal with an ide ending.
STEP 3: Use prefixes to indicate the number of atoms (subscript) of each element.
Table5.12

51. Naming Covalent Compounds
What is the name of SO3?
1. The first nonmetal is S sulfur.
2. The second nonmetal is O named oxide.
3. The subscript 3 of O is shown as the prefix tri.
SO3  sulfur trioxide
The subscript 1 (for S) or mono is understood.

52. Naming Covalent Compounds
Name P4S3.
1. The first nonmetal P is phosphorus.
2. The second nonmetal S is sulfide.
3. The subscript 4 of P is shown as tetra.
The subscript 3 of S is shown as tri.
P4S3  tetraphosphorus trisulfide

53. Formulas and Names of Some Covalent Compounds
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54. Learning Check Select the correct name for each compound.
A. SiCl4 1) silicon chloride
2) tetrasilicon chloride
3) silicon tetrachloride
B. P2O5 1) phosphorus oxide
2) phosphorus pentoxide
3) diphosphorus pentoxide
C. Cl2O7 1) dichlorine heptoxide
2) dichlorine oxide
3) chlorine heptoxide

55. Solution Select the correct name for each compound.
A. SiCl4 3) silicon tetrachloride
B. P2O5 3) diphosphorus pentoxide
C. Cl2O7 1) dichlorine heptoxide

56. Covalent bonds are subclassified as nonpolar or polar

57. Predicting Compounds using Lewis Dot Structures
Going back to the idea of Lewis dot configuration as a good way to keep track of valence electrons for predicting structure of ionic/covalent compounds.

58. Ionic Compounds
Magnesium Iodide using the crossover method to determine the molecular formula and draw the structure using Lewis dot valence electrons.
Step 1: Forming the magnesium cation:
Mg2+ Mg
+ 2e-
Step 2: Forming the iodide anion: I
+ 1e- I

59. Step 3: Putting the ions together
We need 2 iodide anions to balance the +2 charge on the magnesium, as indicated by the formula MgI2 I
Mg2+

60. Covalent Compounds Covalent compounds between oxygen and hydrogen
Step 1: Determine how many bonds are formed by oxygen
Step 2: Determine how many hydrogen atoms are in the chemical formula (hydrogen forms a single bond)
Step 3: Draw the structure

61. Draw the structure for H2O
6 valence e-
2 max bonds H
1 valence e-
1 bond each O H 2
6 valence e-
and
1 valence e-
H2O

62. Covalent Compounds Covalent compounds between carbon and hydrogen
Step 1: Determine how many bonds are formed by carbon
Step 2: Determine how many hydrogen atoms are in the chemical formula (hydrogen forms a single bond)
Step 3: Draw the structure

63. Draw the structure for CH4
4 valence e-
4 max bonds C H
1 valence e-
1 bond each H 4
4 valence e-
and
1 valence e-
CH4 C

64. Chapter Outline Equal Sharing versus Unequal Sharing
When two different kinds of atoms are bonded, the electrons are usually shared unequally.
When a bond exists between two identical kinds of atoms, the electrons are shared equally.
An atom with greater electronegativity has a greater ability to attract shared electrons.

65. Electronegativity

66. Chapter Outline Equal Sharing versus Unequal Sharing (cont)
The greater the difference in electronegativity between two atoms that are covalently bonded, the more polar is the bond.

67. Polar vs. Nonpolar Bonds

68. Paired molecules much different in electronegativity play tug of war
Credit: Courtesy of Julie Millard

69. Chapter Outline States of Matter Review of Types of Bonds
Chemical bonds (intramolecular forces) hold atoms together.
The three types of chemical bonds are ionic, polar covalent, and nonpolar covalent.
Intermolecular forces hold molecules together.

70. Types of Bonds

71. gases < liquids < solids
Chapter Outline
States of Matter (cont)
Particle Cohesion Determines Physical State
In general, the relative strengths of intermolecular forces follows the trend:
gases < liquids < solids
Changes of State
Adding energy breaks intermolecular forces and causes molecules to change their state.
The stronger the intermolecular forces of a compound, the higher are the melting and boiling points.

72. Changes of State

73. Chapter Outline Types of Intermolecular Forces within Pure Substances
London dispersion forces
A temporary dipole in one molecule can induce a dipole in a neighboring molecule.
The negative end of one temporary dipole can attract the positive end of an induced dipole; these attractions are called London dispersion forces.
London forces tend to be fairly weak.

74. Instantaneous dipoles from electron movements

75. London Dispersion Forces

76. Chapter Outline
Types of Intermolecular Forces within Pure Substances (cont)
Dipole-dipole interactions
Dipole-dipole interactions exist between molecules with polar covalent bonds.
Dipole-dipole interactions are typically stronger than London dispersion forces.

77. Dipole-Dipole Interactions

78. Chapter Outline
Types of Intermolecular Forces within Pure Substances (cont)
Hydrogen Bonds
Hydrogen bonds are a special type of dipole-dipole interaction.
Hydrogen bonds can occur when H is bonded to one of the highly electronegative atoms N, O, or F. An example is H2O.
Hydrogen bonds are typically quite strong.

79. Hydrogen Bonds in Water

80. Ice crystal lattice

81. Run the following web animations/movies.
5.6: Electric Current Conduction by Molten Salts
5.8a: Atomic Motion and Thermal Energy
5.9: Atomic Properties of Solids, Liquids, and Gases

82. Chapter Outline Forming Solutions Like dissolves like
Ionic solutes often dissolve in polar solvents; e.g., NaCl dissolves in H2O.
Polar solutes generally dissolve in polar solvents; e.g., NH3 in H2O.
Nonpolar solutes generally do not dissolve well in polar solvents; e.g., oil in H2O.
Run the following web animations/movies.
5.10: Like Dissolves Like Solubility

83. NaCl Dissolving in H2O

84. Polar covalent molecules with dipoles can induce dipoles in nonpolar molecules

85. Why octane molecules and water don't mix

86. Oil and water do not mix
Credit: Visuals Unlimited

87. Chapter Outline Emulsions
Emulsifying agents are molecules that contain a polar portion and a nonpolar region.
Soap is an example of an emulsifying agent that can form a suspension of a nonpolar material in a polar solvent (an “emulsion”).

88. Emulsification with Soap

89. Chapter Outline Measuring Amounts in Solution Solubility Molarity
The maximum amount of a solute that dissolves in a solvent
Molarity
The amount of a solute dissolved in a solvent is its concentration.
Concentration is often measured in moles/liter, also called molarity (M).
Parts per million (ppm)
The concentration of a dilute solution may be measured in parts per million (grams of solute per million grams solution).

90. Solubilities of various Ionic Compounds in Water

91. Key Words Chemical bonds Noble gases Octet rule Ionic compound Ion
Covalent compound
Lewis dot structures
Core electrons
Cation
Anion
Electrostatic forces
Chemical formula
Lone pair
Single bond
Double bond
Triple bond
Isomers
Nonpolar covalent bond
Polar covalent bond
Electronegativity
Dipole
Structure

92. Key Words Intermolecular forces London dispersion forces
Dipole-dipole interactions
Hydrogen bonds
Solution
Solute
Solvent
Aqueous solution
Colloid
Suspension
Amphiphilic/ amphipathic
Emulsion
Solubility
Concentration
Molarity (M)
Parts per million (ppm)