Topic 3: Ionic Bonding

Question 1

Properties of ionic compounds

Answer 1

• have high melting and boiling temperatures. They are solids at room temperature
• are hard but brittle
• do not conduct electricity in the solid state but are good conductors in the liquid state or when dissolved in water or when molten
• they have varying solubilities in water
• they are not soluble in non-polar solvents

Question 2

High melting point

Answer 2

Strong forces between the ions in the 3-D lattice. Need energy to break strong electrostatic forces of attraction
between cations and anions

Question 3

Electrical conductivity

Answer 3

Ionic substances are not able to conduct electricity as solids as the charged particles are not free to move from the lattice. Ionic substances are able to conduct electricity as liquids or molten as ions are free to move in solution/when the ionic substance is melted and can conduct a charge.

Question 4

Solubility

Answer 4

Depends on the relative strength of forces of attraction
between ions and between water molecules and the ions.
If the ionic substance is able to dissolve, then the forces of attraction between the water molecules and ions are greater than that between the ions.

Question 5

General structure of ionic compounds

Answer 5

• Forces between particles are strong
• No free-moving electrons present
• Charge particles (ions) are present but not free to move in the solid state
• When melted, the charged particles (ions) are free to move

Question 6

Ionic bonding model

Answer 6

Metals atoms lose electrons and become cations which have a positive charge. Non-metal atoms gain electrons and become anions which have a negative charge.
An atom’s ability to form a cation or anion depends on how many electrons it must lose or gain to form a stable arrangement of electrons in the outer shell.
Once formed, cations and anions form a 3-D lattice.
Electrostatic forces of attraction between oppositely charged ions hold the 3D lattice together. This is ionic bonding.

Question 7

Hardness

Answer 7

Need energy to break strong electrostatic forces of attraction between cations and anions.

Question 8

Brittleness

Answer 8

If layers of ions move relative to each other, like charges

can be next to each other and repulsion causes the crystal to shatter.

Question 9

Electrolyte

Answer 9

An electrolyte is a solution or molten substance that conducts electricity by the movement of ions.