Metal structure and properties

Question 1

What is an example of a physical property?

Answer 1

• An example of a physical property is the high thermal conductivity of copper. Saucepan bases need to be good conductors of heat. Copper can be used for the base or the whole pan.
• Other physical properties of metal include being lustrous and shiny, malleable or ductile.

Question 2

What is an example of a chemical property?

Answer 2

• An example of a chemical property is the resistance to attack by oxygen or acids shown shown by gold.
• Copper is also resistant, which is another reason why it is used for saucepans.

Question 3

Properties of aluminium

Answer 3

Aluminium has a low density and is use where this property is important, such as in the aircraft industry and also modern cars.

Question 4

What do metals have?

Answer 4

Metals have high melting points and high boiling points, due to their metallic bonds. The bonds between these atoms of very hard to break. A lot of energy is needed to break the bonds.

Question 5

When metals conduct electricity

Answer 5

Electrons in the metal move.

Question 6

What is a metallic bond?

Answer 6

• A metallic bond is a strong electrostatic force of attraction between close-packed positive metal ions and a ‘sea’ of delocalised electrons.
• Metals often have high melting point and boiling points, because a lot of energy is needed to overcome strong attraction between delocalized electrons and the close-packed positive metal ions.

Question 7

What are superconductors?

Answer 7

• Superconductors are materials that conduct electricity with little or no resistance.
• Copper, silver and gold conduct electricity well, but surprisingly do not become superconductors.
• The electrical resistance of mercury suddenly drops to 0 at -268.8°C. This phenomenon is called superconductivity.

Question 8

When a substance goes from its normal state to a superconducting state,

Answer 8

• It no longer has any magnetic field inside it.
  
  • If a small magnet is brought near the superconductor, it is repelled.
  • If a small permanent magnet is placed above the superconductor, it levitates.

Question 9

The potential benefits of superconductors are:

Answer 9

• Loss-free power transmission.
• Super-fast electronic circuits.
• Powerful electromagnets.

Question 10

There needs to be a good deal of development work before the true potential of superconductors is realised.

Answer 10

• They work only at very low temperatures; this limits their use.
• Superconductors that function at 20°C need to be developed.