Metallic Bonding

Question 1

What is a metallic bond?

Answer 1

When MANY electrostatic forces of attraction form between DELOCALISED electrons and the positively charged IONS arranged in a METALLIC LATTICE.

Question 2

What is the structure of a metal known as?

Answer 2

Giant metallic lattice.

Question 3

Draw a diagram to show the structure of a metallic lattice.

Answer 3

Metallic lattice = (Need AT LEAST 9 ions)

9x9 positive ions next to each other.
Include 1+ / 2+ / 3+ in the circles.
For each ion, show the delocalised electrons around it.

Electrons may be represented as e⁻ or a circle with a ‘-‘ symbol.

E.G.
Mg2+ has 2 delocalised electron per ion. So in a 9x9 I would draw 18 electrons.

Question 4

What are the properties of metals?

Answer 4

Conduct electricity (when solid & molten)

Ductile

Malleable

Question 5

What does ductile mean?

Answer 5

When a metal can be drawn into long thin WIRES.

Question 6

What does malleable mean?

Answer 6

When a metal can EASILY be beaten into SHAPE.

Question 7

Why can metals conduct electricity when solid and molten?

Answer 7

Metals contain DELOCALISED electrons, which are mobile charge carriers that carry the current.

Question 8

Why are metals ductile?

Answer 8

LAYERS of metal ions can slide over one another when a force is applied.

Question 9

Suggest why gaseous metals do not conduct electricity.

Answer 9

A sample of gaseous metal contains gas metal ATOMS, not ions.

There aren’t any delocalised electrons in a gas metal - cannot conduct electricity.

Question 10

Explain what is meant by a ‘plasma’

Answer 10

A sample of gaseous IONS, not atoms.

They DO conduct electricity.

Question 11

Give two factors that affect the strength of a metallic bond.

Answer 11

Charge density (charges on the ion)

Size of ion

Question 12

Explain how the charge on metal ions affect the strength of metallic bonding. [2 marks]

Answer 12

The greater the charge on metal ions, the stronger the metallic bonding.

Bc there’s a greater force of attraction between the ions AND EACH of the delocalised electrons (since there’s more)

So more energy required to overcome forces - higher MP/BP.

Question 13

Explain how the size of metal ions affect the strength of metallic bonding. [2 marks]

Answer 13

The smaller the metal ion, the stronger the metallic bonding.

Bc a smaller atomic radius means the positive nucleus is CLOSER to the negative delocalised electrons, so there’s a greater force of attraction and metallic bond.

Question 14

How does the size of an ion change as you go down a group?

Answer 14

The size of ions increases as you go down the group.

Question 15

How does the size of an ion change across a period?

Answer 15

The size of ions decreases across a period.

Question 16

Explain why the size of an ion changes across a period.

Answer 16

The size of an ion decreases across a period.

Bc the charge of the ion increases - there’s a stronger attraction between the + nucleus and the - delocalised electrons. This pulls the electron CLOSER to the ion, making it smaller.

Question 17

Why does aluminium have a higher melting point than potassium? [5 marks]

Answer 17

Al has a higher melting point compared to K because…

K forms a 1+ ion, whereas Al forms a 3+ ion.
This means Al has a greater charge density (has more charge), so there are greater electrostatic forces of attraction between the cation and delocalised electron. This increases the strength of the metallic bond, and more energy is required to overcome the forces.

Al is a smaller ion compared to K, bc the stronger charge on Al holds the delocalised electrons closer to the positive nucleus, making it smaller. This results in a greater force of attraction and thus a stronger metallic bond.

Question 18

What is an alloy?

Answer 18

A mixture of metals.

Question 19

Why are alloys less malleable compared to pure metals?

Answer 19

The layers of ions are distorted, meaning they cannot slide over each other easily.