SC13 Transition Metals, Alloys and Corrosion ✓

Question 1

SC13a - Describe some typical chemical properties of transition metals.

Answer 1

• Usually form coloured compounds (colour decided by the ion involved e.g. copper forms blue compounds)
• Chemical catalysts

Question 2

SC13a - Describe some typical physical properties of transition metals.

Answer 2

• Malleable
• Ductile
• Lustrous (when polished)
• Good conductors of heat and electricity
• High melting points and densities (compared to groups 1 and 2)

Question 3

SC13a - Where are Transition Metals found, on the periodic table?

Answer 3

In the middle of the periodic table, between groups 2 and 3

Question 4

SC13b - How does sacrificial protection work?

Answer 4

• A more reactive metal is attached to Iron or Steel.
• The oxygen and water are going to react with the more reactive metal instead, protecting the iron and steel

Question 5

SC13b - What is corrosion?

Answer 5

When a metal continuously oxidises over time becoming weaker

Question 6

SC13b - What is oxidation in terms of electrons and oxygen?

Answer 6

The loss of electrons and/or the gain of oxygen

Question 7

SC13b - What is rusting?

Answer 7

The corrosion of Iron when it reacts with oxygen and water

Question 8

SC13b - What makes a metal more or less reactive?

Answer 8

• How easily its able to lose its outer shell electrons (this is a combination of how many there are and how far away from the nucleus they are)

Question 9

SC13b - Which metals are typically involved in sacrificial protection?

Answer 9

Zinc or magnesium, protecting iron or steel from rusting

Question 10

SC13b - How can rusting be prevented?

Answer 10

• Keeping air away by storing the metal in an unreactive atmosphere of nitrogen or argon
• Keeping water away, e.g using a desiccant powder that absorbs water vapour
• Painting, coating with plastic, oiling and greasing

Question 11

SC13c - For what two main reasons may a metal be electroplated?

Answer 11

• To improve its appearance
• To improve its resistance to corrosion or rusting
• save money as use less precious metal

Question 12

SC13c - What is galvanising?

Answer 12

• Galvanising can be used to protect iron or steel objects. The object is coated in a layer of zinc, the zinc stops water and oxygen reaching the initial metal and stops corrosion

Question 13

SC13c - What process is used to electroplate a metal?

Answer 13

Electrolysis

Question 14

SC13c - When electroplating, what would you use as the anode and cathode?

Answer 14

• Cathode will be the object you are plating
• Anode will be the metal you are plating it with.
• Electrolyte contains ions of plating material, so they move to the object and are deposited as metal atoms, as they are replaced by ions leaving the anode

Question 15

SC13c - Which two methods can be used to galvanise an object?

Answer 15

Dipping it in molten zinc or electroplating

Question 16

SC13d - What is an alloy?

Answer 16

A mixture of a metal with one or more other (not necessarily metal) elements

Question 17

SC13d - Why are alloys stronger than pure metals [4 marks]

Answer 17

• In a pure metal all the atoms are the same size in a regular structure
• This allows layers to slide over each other easily
• In an alloy, the atoms are different sizes in an irregular structure
• This means layers cannot slide over each other as easily

Question 18

SC13e - Name some uses of gold copper and aluminium linked to their properties that suit its use.

Answer 18

Gold:

• Memory chips - Good conductor of electricity
• Jewellery - Lustrous

Copper:

• Wires - Ductile
• Coins - Cheap and malleable

Aluminium:

• Overhead cables - Low density

Question 19

SC13e - Name some uses of magnalium, brass and nitinol linked to their properties that suit its use.

Answer 19

Magnalium (Magnesium and aluminium):

• Lightweight mechanical parts
  
  • Low density
  • High strength

Brass (Copper and zinc):

• Plug in points
  
  • Corrosion resistant
  • Good conductor of electricity

Nitinol (Nickel and Titanium):

• Braces and glasses frames
  
  • Shape memory allows it to have 2 shapes depending on pressure or temperature.

Question 20

SC13c - Why are some high end electrical connectors plated with gold?

Answer 20

• To improve their resistance to corrosion