1. Chemical Bonding and Nomenclature
Chapter 5

2. What is a Molecule ? Molecule Elemental molecules
A collection of atoms bonded together
Elemental molecules
Atoms from same element
Diatomic: H2, N2, F2 , O2, I2, Cl2 , Br2
Polyatomic: P4, S8

3. What is a Molecule Molecules of Compounds Atoms of different elements
Simple vs. Complicated
Small vs. extremely large

4. Properties of Molecules
Molecules have different properties than their elemental component.
Element
Properties O
Odorless, colorless very reactive toxic gas H
Odorless colorless gas reactive

5. Properties of Molecules
Colorless odorless gas moderately reactive not flammable H2
Colorless odorless gas moderately reactive flammable
H2O
Colorless odorless liquid, low reactivity
H2O2
Colorless odorless liquid high reactivity

6. Why do molecules form? To be like the noble gases
The noble gases are perfect hence they do not react with anything
They have 8 valence electrons in their outer most shell

7. Valence Electrons?
The outermost electrons. Determines the chemical properties of an element
The only electrons that bond
The roman numerals at the top of each group A element
Most elements prefer to have 8 electrons this is called the octet rule. Why?

8. The Octet Rule
Atoms tend to gain, lose, or share electrons until they have eight valence electrons.

9. X Electron Dot diagrams A way of keeping track of valence electrons.
How to write them
Write the symbol.
Put one dot for each valence electron
Don’t pair up until you have too. X

10. The Electron Dot diagram for Nitrogen
Nitrogen has 5 valence electrons.
First we write the symbol. N
Then add 1 electron at a time to each side.
Until they are forced to pair up.

11. Write the electron dot diagram forNa Mg C O F Al He

12. Electron Configurations for Cations
Metals lose electrons to attain noble gas configuration.
They make positive ions.

13. Electron Dots For Cations
Metals will have few valence electrons Ca

14. Electron Dots For Cations
Metals will have few valence electrons
These will come off Ca

15. Electron Dots For Cations
Metals will have few valence electrons
These will come off
Forming positive ions
Ca+2

16. Electron Configurations for Anions
Nonmetals gain electrons to attain noble gas configuration.
They make negative ions.

17. Electron Dots For Anions
Nonmetals will have many valence .electrons.
They will gain electrons to fill outer shell. P
P-3

18. Stable Electron Configurations
All atoms react to achieve noble gas configuration.
Noble gases 8 valence electrons .
Also called the octet rule. Ar

19. Covalent Bonding

20. How does H2 form?
The nuclei repel + +

21. How does H2 form? + + The nuclei repel
But they are attracted to electrons
They share the electrons + +

22. Covalent bonds Nonmetals hold onto their valence electrons.
They can’t give away electrons to bond.
Still want noble gas configuration.
Get it by sharing valence electrons with each other.
By sharing both atoms get to count the electrons toward noble gas configuration.

23. Covalent bonding
Fluorine has seven valence electrons F

24. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven F F

25. F F Covalent bonding Fluorine has seven valence electrons
A second atom also has seven
By sharing electrons F F

26. Single Covalent Bond A sharing of two valence electrons.
Only nonmetals and Hydrogen.

27. How to show how they formed
It’s like a jigsaw puzzle.
I have to tell you what the final formula is.
You put the pieces together to end up with the right formula.
For example- show how water is formed with covalent bonds.

28. H O Water Each hydrogen has 1 valence electron
Each hydrogen wants 1 more
The oxygen has 6 valence electrons
The oxygen wants 2 more
They share to make each other happy H O

29. H O Water Put the pieces together The first hydrogen is happy
The oxygen still wants one more H O

30. H O H Water The second hydrogen attaches
Every atom has full energy levels H O H

31. Multiple Bonds
Sometimes atoms share more than one pair of valence electrons.
A double bond is when atoms share two pair (4) of electrons.
A triple bond is when atoms share three pair (6) of electrons.

32. C O Carbon dioxide CO2 - Carbon is central atom ( I have to tell you)
Carbon has 4 valence electrons
Wants 4 more
Oxygen has 6 valence electrons
Wants 2 more C O

33. Carbon dioxide
Attaching 1 oxygen leaves the oxygen 1 short and the carbon 3 short C O

34. Carbon dioxide
Attaching the second oxygen leaves both oxygen 1 short and the carbon 2 short O C O

35. Carbon dioxide
The only solution is to share more O C O

36. Carbon dioxide
The only solution is to share more O C O

37. Carbon dioxide
The only solution is to share more O C O

38. Carbon dioxide
The only solution is to share more O C O

39. Carbon dioxide
The only solution is to share more O C O

40. Carbon dioxide
The only solution is to share more O C O

41. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond O C O

42. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond
8 valence electrons O C O

43. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond
8 valence electrons O C O

44. O C O Carbon dioxide The only solution is to share more
Requires two double bonds
Each atom gets to count all the atoms in the bond
8 valence electrons O C O

45. F B F F H O H N O F F F S F A. Octet Rule Very unstable!! Exceptions:
Hydrogen  2 valence e-
Groups 1,2,3 get 2,4,6 valence e-
Expanded octet  more than 8 valence e- (e.g. S, P, Xe)
Radicals  odd # of valence e-

46. B. Drawing Lewis Diagrams
Find total # of valence e-.
Arrange atoms - singular atom is usually in the middle.
Form bonds between atoms (2 e-).
Distribute remaining e- to give each atom an octet (recall exceptions).
If there aren’t enough e- to go around, form double or triple bonds.

47. B. Drawing Lewis Diagrams
CF4
1 C × 4e- = 4e-
4 F × 7e- = 28e-
32e- F
F C F
- 8e-
24e-

48. B. Drawing Lewis Diagrams
BeCl2
1 Be × 2e- = 2e-
2 Cl × 7e- = 14e-
16e-
Cl Be Cl
- 4e-
12e-

49. B. Drawing Lewis Diagrams
CO2
1 C × 4e- = 4e-
2 O × 6e- = 12e-
16e-
O C O
- 4e-
12e-

50. C. Polyatomic Ions To find total # of valence e-:
Add 1e- for each negative charge.
Subtract 1e- for each positive charge.
Place brackets around the ion and label the charge.

51. O O Cl O C. Polyatomic Ions ClO4- 1 Cl × 7e- = 7e- 4 O × 6e- = 24e-

52. H H N H C. Polyatomic Ions NH4+ 1 N × 5e- = 5e- 4 H × 1e- = 4e- 9e-

53. D. Resonance Structures
Molecules that can’t be correctly represented by a single Lewis diagram.
Actual structure is an average of all the possibilities.
Show possible structures separated by a double-headed arrow.

54. D. Resonance Structures
O S O O
O S O O
O S O

55. Practice
Complete the worksheet

56. Nomenclature-Naming Chemical Compounds

57. Atoms and ions Atoms are electrically neutral.
Same number of protons and electrons.
Ions are atoms, or groups of atoms, with a charge.

58. Atoms and Ions Different numbers of protons and electrons.
Only electrons can move.
Gain or lose electrons.

59. F-1 O-2 Anion A negative ion. Has gained electrons.
Non metals can gain electrons.
Charge is written as a super script on the right.
F-1
Has gained one electron
O-2
Has gained two electrons

60. K+1 Ca+2 Cations Positive ions. Formed by losing electrons.
More protons than electrons.
Metals form cations.
K+1
Has lost one electron
Ca+2
Has lost two electrons

61. Two Types of Compounds Molecular compounds Made of molecules.
Made by joining nonmetal atoms together into molecules.

62. Two Types of Compounds Ionic Compounds Made of cations and anions.
Metals and nonmetals.
The electrons lost by the cation are gained by the anion.
The cation and anions surround each other.
Smallest piece is a FORMULA UNIT.

63. Formula Unit
The smallest whole number ratio of atoms in an ionic compound.
Ions surround each other so you can’t say which is hooked to which.

64. Two Types of Compounds Ionic Molecular Smallest piece Formula Unit
Molecule
Types of elements
Metal and Nonmetal
Nonmetals
Solid, liquid or gas
State
solid
Melting Point
High >300ºC
Low <300ºC

65. Chemical Formulas
Shows the kind and number of atoms in the smallest piece of a substance.
Molecular formula- number and kinds of atoms in a molecule.
CO2

66. Charges on ions
For most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location.
Elements in the same group have similar properties.
Including the charge when they are ions.

67. +1 +2 +3 -3 -2 -1

68. Naming ions We will use the systematic way.
Cation- if the charge is always the same (Group A) just write the name of the metal.
Transition metals can have more than one type of charge.
Indicate the charge with roman numerals in parenthesis.

69. Name these
Na+1
Ca+2
Al+3
Fe+3
Fe+2
Pb+2
Li+1

70. Write Formulas for these
Potassium ion
Magnesium ion
Copper (II) ion
Chromium (VI) ion
Barium ion
Mercury (II) ion

71. Naming Anions Anions are always the same.
Change the element ending to – ide
F-1 Fluoride

72. Name these
Cl-1
N-3
Br-1
O-2

73. Write these
Sulfide ion
iodide ion
phosphide ion
Strontium ion

74. Polyatomic ions Groups of atoms that stay together and have a charge.
Acetate C2H3O2-1
Nitrate NO3-1
Nitrite NO2-1
Hydroxide OH-1
Permanganate MnO4-1
Cyanide CN-1

75. Polyatomic ions Sulfate SO4-2 Sulfite SO3-2 Carbonate CO3-2
Chromate CrO4-2
Dichromate Cr2O7-2
Phosphate PO4-3
Phosphite PO3-3
Ammonium NH4+1

76. Ions and Ionic Compounds

77. Naming Binary Ionic Compounds
Binary Compounds - 2 elements.
Ionic - a cation and an anion.
To write the names just name the two ions.
Easy with Representative elements.
Group A
NaCl = Na+ Cl- = sodium chloride
MgBr2 = Mg+2 Br- = magnesium bromide

78. Naming Binary Ionic Compounds
The problem comes with the transition metals.
Need to figure out their charges.
The compound must be neutral.
same number of + and – charges.
Use the anion to determine the charge on the positive ion.

79. Naming Binary Ionic Compounds
Write the name of CuO
Need the charge of Cu
O is -2
copper must be +2
Copper (II) oxide
Name CoCl3
Cl is -1 and there are three of them = -3
Co must be +3 Cobalt (III) chloride

80. Naming Binary Ionic Compounds
Write the name of Cu2S.
Since S is -2, the Cu2 must be +2, so each one is +1.
copper (I) sulfide
Fe2O3
Each O is -2
Fe must be = + 3
iron (III) oxide

81. Naming Binary Ionic Compounds
Write the names of the following:
KCl
Na3N
CrN
Na2Se

82. Ternary Ionic Compounds
Will have polyatomic ions
At least three elements
name the ions
NaNO3
CaSO4
CuSO3
(NH4)2O

83. Ternary Ionic Compounds
LiCN
Fe(OH)3
(NH4)2CO3
NiPO4

84. Writing Formulas The charges have to add up to zero.
Get charges on pieces.
Cations from name of table.
Anions from table or polyatomic.
Balance the charges.
Put polyatomics in parenthesis.

85. Writing Formulas Write the formula for calcium chloride.
Calcium is Ca+2
Chloride is Cl-1
Ca+2 Cl-1
CaCl2

86. Write the formulas for these
Lithium sulfide
tin (II) oxide
tin (IV) oxide
Magnesium fluoride
Copper (II) sulfate
Iron (III) phosphide
gallium nitrate
Iron (III) sulfide

87. Write the formulas for these
Ammonium chloride
ammonium sulfide
barium nitrate

88. Things to look for If cations have (), the number is their charge.
If anions end in -ide they are probably off the periodic table (Monoatomic)
If anion ends in -ate or -ite it is polyatomic

89. Molecular Compounds

90. Molecular compounds made of just nonmetals
smallest piece is a molecule
can’t be held together because of opposite charges
can’t use charges to figure out how many of each atom

91. Easier Ionic compounds use charges to determine how many of each
Have to figure out charges
Have to figure out numbers
Molecular compounds name tells you the number of atoms
Uses prefixes to tell you the number

92. Prefixes 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta-
8 octa-

93. Prefixes
9 nona-
10 deca-
One exception is we don’t write mono- if there is only one of the first element.

94. Name These
N2O
NO2
Cl2O7
CBr4
CO2
BaCl2

95. Write formulas for these
diphosphorus pentoxide
tetraiodide nonoxide
sulfur hexaflouride
nitrogen trioxide
Carbon tetrahydride
phosphorus trifluoride
aluminum chloride

96. Naming Acids a little tricky so pay attention

97. Acids Compounds that give off hydrogen ions when dissolved in water
Must have H in them (somewhere)
will always be some H next to an anion
The anion determines the name.

98. Naming acids
If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid
HCl - hydrogen ion and chloride ion
hydrochloric acid
H2S hydrogen ion and sulfide ion
hydrosulfuric acid

99. Naming Acids If the anion has oxygen in it it ends in -ate or -ite
change the suffix -ate to -ic acid
HNO3 Hydrogen and nitrate ions
Nitric acid
change the suffix -ite to -ous acid
HNO2 Hydrogen and nitrite ions
Nitrous acid

100. Name these HF
H3P
H2SO4
H2SO3
HCN
H2CrO4

101. Writing Formulas Hydrogen will always be first
name will tell you the anion
make the charges cancel out.
Starts with hydro- no oxygen, -ide
no hydro, -ate comes from -ic, -ite comes from -ous

102. Write formulas for these
hydroiodic acid
acetic acid
carbonic acid
phosphorous acid
hydrobromic acid
Perchloric acid
Dichromic acid
Oxalic acid