I. Introduction
A. What is a bond?
A mutual attraction between the electrons of
2 atoms that binds them together
B. How do bonds form?
Electrons are either shared or transferred
between atoms
C. Terms:
a. Energy Levels: The “shells” of an atom where the
electrons are located (found from the rows on
the periodic table)
b. Valence electrons: the outer shell electrons
(ones on the outer most energy level)
D. Atom Pictures
1. Hydrogen
2. Helium
D. Atom Pictures
3. Lithium
4. Beryllium
**Why are valence electrons important?
II. Lewis Structures
A. What is a Lewis Structure?
A way to represent the valence electrons in an atom
B. Basic Notation:
II. Lewis Structures
C. How to find the number of valence electrons for
main group elements:
Look at the columns (groups) on the periodic
table. Only works for main group elements
Column #
Valence
Electrons
1
1
2
2
13
Transition
Metals
(vary – will
be given)
3
14
4
15
5
16
6
17
7
18
8
(He 2)
Element
# of valence
electrons
Lewis Dot
Structure
Element
Hydrogen
Aluminum
Helium
Chlorine
Sodium
Oxygen
Carbon
Krypton
# of valence
electrons
Lewis Dot
Structure
Warm-up 1/31/13
Element
1. Sulfur
2. Calcium
3. Nitrogen
4. Lithium
5. Argon
6. Rubidium
# of Valence electrons
Lewis structure
Warm-up 2/1/13
Element
1. Sulfur
2. Nitrogen
3. Rubidium
4. Argon
# of Valence electrons
Lewis structure
Why do elements form compounds?
To become more stable elements
Octet Rule: All atoms want a full outer shell.
Most want 8 (oct = 8), H wants 2
**All elements want a ____________________
and be like a _______________________.
III. Ionic Bonds: Transfer of electrons
between a metal and a nonmetal
A. Terms:
a. Ion: An element with an overall charge (unequal
numbers for p+ and e-)
b. Cation: A positive ion
c. Anion: A negative ion
A.Lewis structure to ion:
Element
Lithium
Sodium
Magnesiu
m
Calcium
Oxygen
Sulfur
Fluorine
Chlorine
Gain/Lose?
Lewis
structure How Many?
Charge
Metal/
Nonmetal
?
Cation/
Anion?
B. Properties of ionic bonds:
•
•
•
•
Form solid crystals at room temperature
Hard, brittle
High melting temperatures (boiling points)
Tend to dissolve in water (breaks into ions)
– Conducts electricity when melted or dissolved
in water (electrolyte). Solids do not conduct.
Properties
How Salt Dissolves in Water
C. Forming Ionic Bonds
1) GOAL: All atoms have a full outer shell
2) Metals lose electrons to become like noble gases.
3) Nonmetals gain electrons to become like noble
gases
4) Each element wants a full outer shell
Transfer of Electrons
5) Lewis Structure Examples:
Elements
Lithium and
Bromine
Calcium and Oxygen
Sodium and Oxygen
Metal
Lewis
Structure
Nonmetal
Lewis
Structure
Ionic Bond
6) Charge examples:
Elements
Lithium and
Bromine
Calcium and
Oxygen
Sodium and
Oxygen
Metal
Charge
Nonmetal
Charge
Ionic Bond
Ionic Exit 1/31/13:
1. Show how potassium and iodine bonds.
2. Show how rubidium and oxygen bonds.
3. Show how aluminum and fluorine bonds.
Warm-up 2/4/13
1. Show how lithium and fluorine bond
2. Show how aluminum and oxygen bond
D. Naming Ionic Compounds
a. RULES FOR NAME TO FORMULA
1. Write the metal and charge first (if RN –
that is the charge on the metal)
2. Write the nonmetal and charge second
3. Cross and bring down numbers; remove
charges and CHECK!
HINT: All charges should add to zero
b. EXAMPLES
1.Sodium chloride
2. Iron (III) oxide
3. Potassium oxide
4. Tin (IV) selenide
5. Aluminum sulfide
Practice 1
1.
2.
3.
4.
5.
Aluminum fluoride
Calcium bromide
Iron (III) chloride
Silver (I) chloride
Lead (II) oxide
c. RULES FOR FORMULA TO NAME
1. Name the metal (cation) first
a. If a transition metal, write roman numeral (need
to figure out charge)
2. Name the nonmetal (anion) second
a. Change ending to -ide
d. EXAMPLES
1.NaF
2. MgO
3. CaCl2
4. CuBr2
5. Al2O3
Practice 2
1.
2.
3.
4.
5.
MgBr2
Cs2O
TiF3
NiO
AuCl3
E. Naming with Polyatomic Ions
a. Polyatomic Ion:
• Covalently bonded molecules with a charge
• Combine with metals to form ionic
compounds
b. Follow rules for naming ionic compounds; be aware
that compounds with polyatomic ions will have more
than 2 elements.
Pictures
c. Examples:
Name to Formula:
1.Sodium hydroxide
2. Calcium phosphate
3. sodium carbonate
4. Aluminum nitrate
5. Calcium hydroxide
Formula to Name:
1.KMnO4
2. NaCH3COO
3. Al2(SO4)3
4. Ca(CN)2
5. NaOH
Practice 3
1.
2.
3.
4.
5.
Gold (III) cyanide
Silver (I) nitrate
Tin (IV) sulfate
Sodium acetate
Ammonium hydroxide
1.
2.
3.
4.
5.
KClO4
Li2Cr2O7
(NH4)2S
NaHCO3
Na2CO3
IV. Covalent Bonds: Sharing of
electrons between 2 nonmetals.
A.Terms:
a. Polar: Unequal sharing of
electrons (think “pulling”)
b. Nonpolar: Equal sharing of
electrons (think “not
pulling”)
c. Review: Remember – like
dissolves like
B. Properties of Covalent Bonds
• May be solids, liquids or gases at room
temperature
• Most have low melting points (boiling points)
– There are exceptions (EX: diamonds)
• Poor conductors of heat and electricity
– do not conduct (well or not at all) when dissolved
in water
C. Forming Covalent Bonds
1) GOAL: Atoms will share electrons to get a full
outer shell
2) Exceptions to Octet Rule:
H only wants 2 eB only wants 6 eS and P can have more than 8
Molecule
H2O (water)
CF4 (carbon tetrafluoride)
Total valence electrons
Lewis Structure
D. Naming Covalent Compounds
GREEK PREFIXES (starter)
Number Prefix
1
Mono-
2
Di-
3
Tri-
4
Tetra-
5
Penta-
6
Hexa-
7
Hepta-
8
Octa-
9
Nona-
10
Deca-
Other uses for these prefixes
a. RULES FOR NAME TO FORMULA
1.
2.
3.
4.
Write the symbol for the first element
Look at the prefix – this is the subscript
Write the symbol for the second element
Look at the prefix – this is the subscript
b. EXAMPLES
1.Nitrogen tribromide
2. Dinitrogen trisulfide
3. Carbon monoxide
4. Tetraphosphorus
decoxide
5. Carbon tetrahydride 6. Diboron hexahydride
c. RULES FOR FORMULA TO NAME
1. Name the first element
a. Use the subscript to determine the Greek
Prefix
b. No prefix needed for only one atom
2. Name second element
a. Use subscript to determine the prefix
(always)
b. Change ending to -ide
d. EXAMPLES
1.CO2
2. H2O
3. P2O5
4. CCl4
5. CF4
REVIEW:
Describe each type of bond shown in
the picture below:
V. Metallic Bonds: a
lattice of positive ions
in a sea of electrons
A. Properties:
• Good Conductors of heat and electricity
• Malleable (flattened into sheets)
• Ductile (pulled into wires)
• Solids at room temperature (except Mercury)
Video
IV. Examples
a. Classify the following compounds as having
Ionic (I), Covalent (C), or Metallic (M) bond.
a.CuCl2
b.CO2
c.Ag
d.NaCl
e.O2
f.Fe2O3
g.H2O
h. Na
i.CaF2
j.H2
________
________
________
________
________
________
________
________
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________
Review – Exit
Type of bond
Between metals and/or nonmetals
Ionic
Covalent
Metallic
1. What is a cation?
2. What is a anion?
Electrons…