Ionic Compounds
LG: I can write formulas and draw Lewis
structures for ionic compounds
Chemical Compounds
• A compound is a group of two or more
atoms/ions held together by chemical bonds
– Compounds can be ionic or molecular
• A chemical bond is the force holding two
atoms or ions together in a compound
(“invisible glue”)
– Chemical bonds can be ionic or covalent
Formation of Ionic Compounds
• An ionic compound forms when a nonmetal
removes an electron from a metal.
– The resulting ions have opposite charge and are
attracted to each other
– This electrostatic attraction is an ionic bond
Structure of Ionic Compounds
• Ionic compounds do not exist in
the simplest ratio of ions; they
form large arrangements called
crystal lattice structures
• Crystals of different ionic
compounds have different 3-D
shapes
• The smallest repeating unit is
called a formula unit
Properties of Ionic Compounds
• Hard & have high melting and
boiling points
– Each +ve ion is attracted to many –ve
ions (& vice versa); bonds resist being
stretched
• Brittle
– A sudden force offsets the lattice
structure and causes ions with the
same charge to come into contact and
repel
• Ionic compound are soluble in water
and form electrolytes
– Ions separate from one another and
can carry electric charge
Using Lewis Structures to Represent
Ionic Bonds
• Lewis Dot Diagrams for atoms:
– ie.
• Lewis Dot diagrams for ions:
– ie.
• Lewis structures for ionic compounds:
– Ie.
• The lowest ratio of ions that produces a neutral compound
is the chemical formula: NaCl
Practice: Lewis Structures
• Draw Lewis diagrams for the following atoms:
Mg Li
F
O
N
K
Ca
S
• Draw Lewis for each element above as an ion:
• Draw Lewis structures for the following ionic compounds:
Lithium Fluoride
Magnesium Fluoride
Potassium Oxide
Calcium Sulfide
Lithium Nitride
Magnesium Nitride
• Write chemical formulas for each compounds above:
Homework
• New Book: Pg. 60 # 1 – 5, 7, 8
• Old Book: Pg. 71 # 1 – 5, Pg. 73 # 9, Pg. 74 # 11