Module 6 Lesson 2 Ionic Bonds and Ionic Compounds

Module 6 Lesson 2: Ionic Bonds and Ionic Compounds

Focus Question

How are the ions in ionic compounds
arranged?

New Vocabulary

ionic bond

ionic compound

crystal lattice

electrolyte

lattice energy

Review Vocabulary

compound: a chemical combination of two or
more different elements

Formation of an Ionic Bond

• The electrostatic force that holds oppositely

charged particles together in an ionic
compound is called an ionic bond.

• Compounds that contain ionic bonds are ionic

compounds.

• If ionic bonds occur between metals and the

nonmetal oxygen, oxides form.

• Most other ionic compounds are salts.

Multiple Choice

Ionic bonds form between metals and nonmetals.

• true

• false

Multiple Choice

How are ionic bonds formed?

• electrostatic forces between ions

• 
  sharing of electrons between atoms

• gain of electrons by atoms

• loss of electrons by atoms

Formation of an Ionic Bond

• Binary ionic compounds contain a metallic

cation and a nonmetallic anion.

• Binary means that the compounds contain

only two different elements.

• Sodium chloride (NaCl) is a binary compound.

Multiple Choice

In the ionic solid sodium chloride (NaCl), there is a __________________ sodium ions to chlorine ions.

• one and a half to one

• two to one

• one to one

• one to two

Match

Determine the ratio of cations to anions in each.

• potassium chloride (KCl)

• calcium fluoride (CaF₂)

• sodium oxide (Na₂O)

• potassium nitride (K₃N)

1:1

1:2

2:1

3:1

• 1:1

• 1:2

• 2:1

• 3:1

Properties of Ionic Compounds

• Electrical forces in ionic bonds produce

unique physical structures.

• In an ionic compound, large numbers of

positive ions and negative ions exist together
in a ratio determined by the number of
electrons transferred from the metal atom to
the nonmetal atom.

Properties of Ionic Compounds

• The ions are packed into a regular repeating

pattern that balances the forces of attraction
and repulsion between the ions.

• The resulting ionic

crystal has a highly
organized nature
with consistent
spacing of ions and
a uniform pattern.

Properties of Ionic Compounds

• The strong attractions among the positive

ions and the negative ions in an ionic
compound result in the formation of a crystal
lattice.

• A crystal lattice is a three-dimensional

geometric arrangement of particles.

Multiple Choice

In a crystal lattice, each positive ion is surrounded by negative ions.

• true

• false

Properties of Ionic Compounds

• Melting point, boiling point, and hardness are

physical properties. They are determined by
the strength of electrical forces between
particles in matter.

• Ionic bonds are relatively strong, so ionic

crystals require a lot of energy to break. Thus,
the crystals have high melting and boiling
points.

Multiple Choice

Ionic crystals have high melting points and high boiling points because ________.

• ionic bonds are relatively weak

• ionic bonds are relatively strong

• 
  ionic solids are excellent conductors of electricity

• ionic liquids do not conduct electricity

Properties of Ionic Compounds

Properties of Ionic Compounds

• Ionic crystals are hard, rigid, brittle solids due

to the strong attraction between electric
charges that hold the ions in place.

• This figure shows how and why crystals break

when a force strong enough to overcome
these attractive forces is applied.

Multiple Choice

When an ionic compound is struck, it often shatters. What force breaks the ionic crystal apart?

• gravity

• 
  electrostatic attraction

• 
  the force of the blow

• electromagnetic repulsion

Properties of Ionic Compounds

• The ability of a material to conduct electricity

depends on the availability of freely moving
charged particles.

• In a solid, ions are locked in position by strong

attractive forces. Thus, ionic solids are poor
conductors.

• In ionic compounds in solution or a liquid

state, ions are free to move. Thus, these
compounds conduct electricity.

• An ionic compound whose aqueous solution

conducts an electric current is called an
electrolyte.

Multiple Choice

An ionic compound that will conduct an electric current when it forms an aqueous solution is a(n)

• molecular compound

• crystal lattice

• nonelectrolyte

• electrolyte

Multiple Select

Identify three physical properties of ionic compounds

• high melting point

• low melting points

• hard, rigid crystals

• high boiling point

• non-crystal

Energy and the Ionic Bond

• Reactions that absorb energy are

endothermic.

• Reactions that release energy are exothermic.
• The formation of ionic compounds from

positive ions and negative ions is always
exothermic.

• The attraction of the ions forms a more stable

system that is lower in energy than the
individual ions.

Energy and the Ionic Bond

• The energy required to separate 1 mol of ions

of an ionic compound is the lattice energy.

• The strength of the electrical forces holding

ions in place is reflected by the lattice energy.

• The greater the lattice energy, the stronger

the force of attraction.

Energy and the Ionic Bond

• Lattice energy is related to ion size.
• The electrostatic force of attraction between

opposite charges increases as the distance
between the charges decreases.

• Smaller ions form compounds with more

closely spaced ionic charges, so they have
stronger attractions and greater lattice
energies.

• Ionic bonds formed from ions with larger

positive or negative charges also have greater
lattice energy.

Energy and the Ionic Bond

Multiple Choice

The more negative the lattice energy is, the stronger is the force of attraction between the ions of an ionic compound.

• true

• false