Ionic and Metallic Bonding
7.2 Ionic Bonding and Ionic
Compounds
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
Think about it.
• Sodium is very reactive
• Chlorine is very poisonous
• Why do these very caustic
materials combine to
produce such an inert
substance, table salt?
• Why do they react at all?
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
Formation of Ionic
Compounds
• Compounds composed of cations and
anions are called ionic compounds.
• Ionic compounds are electrically
neutral.
– Ionic compounds are usually composed of
metal cations and nonmetal anions.
– These ions will cancel out each other’s
charge.
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
1
The Ionic Bond
• Cations and Anions have opposite charges.
• The ions attract each other like opposite
poles of two magnets.
• The electrostatic force that holds ions
together in ionic compounds are called ionic
bonds.
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
Formula Units
• Chemists represent the composition of
substances by writing chemical
formulas.
– A chemical formula shows the kinds and
numbers of atoms in the smallest
representative unit of the substance.
– A formula unit is the lowest whole
number ratio of ions in an ionic compound.
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
To review
• Use the electron dot structures to
determine chemical formulas of the
ionic compounds formed when the
following elements combine.
– Magnesium and Chlorine
– Aluminum and Sulfur
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
2
Properties of Ionic
Compounds
• Most ionic compounds are crystalline
solids at room temperature.
• Ionic compounds generally have high
melting points.
• Why are crystalline ionic compounds
generally so rigid and brittle?
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
Properties of Ionic
Compounds
• Coordination number of an
ion is the number of ions of
opposite charge that
surround the ion in a crystal.
• Ionic compounds can
conduct an electric current
when melted or dissolved in
water
The Nora School
955 Sligo Avenue
Silver Spring, Maryland 20910
Chemistry
Period _______
3