5.2 - Ionic bonding and structure

Question 1

What is ionic bonding?

Answer 1

The electrostatic attraction between positive and negative ions

Question 2

Draw the dot and cross diagram of potassium fluoride, KF

Answer 2

:)

Question 3

Draw the dot and cross diagram of magnesium chloride, MgCl₂

Answer 3

:)

Question 4

What are ionic compounds?

Answer 4

Compounds formed when a metal and non-metal react with eachother

Question 5

What is the structure of ionic compounds?

Answer 5

A giant ionic lattice

Question 6

What is a giant ionic lattice?

Answer 6

A three dimensional structure of oppositely charged ions, bonded together by strong ionic bonds

Question 7

Why do most ionic compounds have high melting and boiling points?

Answer 7

• At room temperature, there is insufficient energy to overcome the electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice
• High temperatures are needed to provide the sufficient energy required to overcome the electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice

Question 8

What effect does ionic charge have on melting points of lattices?

Answer 8

The melting points are higher for lattices with greater ionic charges
- as there is a stronger attraction between ions

Question 9

What does ionic attraction also depend on?

Answer 9

The size of the ions

Question 10

Explain why ionic compounds dissolve in water

Answer 10

• Polar water molecules are attracted to the ions on the surface of the ionic lattice
• Bonds form between the polar water molecules and ions, weakening the ionic bonds
• The ionic bonds break
• The ions become surrounded by water molecules and break free from the lattice

Question 11

Why do larger ionic charges decrease solubility?

Answer 11

• The ionic attraction may be too strong for water to be able to break down the lattice structure
• So the ionic compound will not be very soluble

Question 11

In what state do ionic compounds conduct electricity?

Answer 11

Liquid or aqueous states

Question 12

Why don’t ionic compounds conduct electricity in the solid state?

Answer 12

• Ions are in a fixed position in the giant ionic lattice
• There are no mobile charge carriers
• So an ionic compound is a non-conductor of electricity in the solid state

Question 13

Why do ionic compounds conduct electricity when liquid or dissolved in water?

Answer 13

• The solid ionic lattice breaks down
• The ions are free to move as mobile charge carriers
• So an ionic compound is a conductor of electricity in liquid or aqueous states