Metals, Alloys and Corrosion (1)

Question 1

What are

transition metals?

Answer 1

the central block of metals in the middle of the periodic table

Question 2

What are the

properties of transition metals?

(8)

Answer 2

• hard
• strong
• shiny
• malleable
• conduct heat and electricity well
• high melting points (with the exeption of mercury)
• high densities
• colourful (when in a compound)

(boldened properties are not the same as typical properties of metals)

Question 3

What are some uses of

copper?

and why is it used for these purposes? (2)

Answer 3

1. Water pipes - it is malleable and corrosion resistant
2. Electrical wires - it is a good electrical conductor

Question 4

What is a

general use of all transition metals?

Answer 4

catalysts

Question 5

Why are

alloys stronger and harder than pure metals?

Answer 5

Pure metals have a regular arrangement of identical ions so layers can slide over each other and are malleable. As different elements have different sized atoms, adding an element will disrupt the layers of pure atoms, making it more difficult for them to slide over each other.

Question 6

What are some specific properties of

iron?

and why is this important?

Answer 6

• soft
• easily shaped

this makes it too bendy for most uses

Question 7

What elements are added to iron to make

low-carbon steel?

what are the properties of this alloy? (1)

and what is it used for? (1)

Answer 7

(iron) + carbon 0.1-0.3%

it is easily shaped

it is used for car bodies

Question 8

What elements are added to iron to make

high-carbon steel?

what are the properties of this alloy? (3)

and what is it used for? (2)

Answer 8

(iron) + carbon 0.22-2.5%

it is very strong, inflexible and brittle

it is used for blades for cutting tools and bridges

Question 9

What elements are added to iron to make

stainless steel?

what are the properties of this alloy? (2)

and what is it used for? (2)

Answer 9

(iron) + carbon + chromium + nickel (sometimes)

it is corrosion-resistant and hard

it is used for cutlery and containers for corrosive substances

Question 10

What are some

uses of steel?

(8)

Answer 10

• bridges
• engine parts
• cutlery
• washing machines
• pans
• ships
• tools
• cars

Question 11

What are some

common alloys?

(5)

Answer 11

• steel
• brass
• bronze
• gold alloy
• magnalium

Question 12

Tell me about

brass.

and give two uses.

• materials?
• appearance?
• malleability?

Answer 12

• an alloy of copper and zinc
• gold-like appearance
• quite malleable

it is often used in water taps and door fittings

Question 13

Tell me about

gold alloys.

and give a use.

• materials?
• hardness?

Answer 13

• an alloy of gold and a combination of zinc, copper and silver
• hard

it is used to make jewellery

Question 14

Tell me about

magnalium.

and give two uses.

• materials?
• strength?
• relative weight?
• corrosion resistance?

Answer 14

• an alloy of aluminium and magnesium
• strong
• lightweight
• corrodes less easily than pure aluminium

it is used to make parts of an aeroplane and fireworks

Question 15

Define

corrosion.

Answer 15

the reaction of metals with the oxygen and water in their environment

Question 16

What is the general equation for

corrosion.

Answer 16

metal + water + oxygen -> hydrated metal oxide

Question 17

What are the

two main ways of preventing corrosion?

Answer 17

1. Creating a barrier
2. Sacrifical method

Question 18

How does

creating a barrier work to prevent corrosion?

and what are a few different ways of doing this? (4)

Answer 18

it keeps oxygen, water or both away from the metal to prevent corrosion

• painting the metal
• coating the metal in plastic
• electroplating
• oiling or greasing

Question 19

What is

electroplating?

and how does this work?

Answer 19

A process that uses electrolysis to coat the surface of one metal with another metal.

The cathode is the object that is going to be electroplated and the anode is a bar of the metal that will end up coating the surface of the object. The electrolyte is a solution containing the metal ions of the metal that is being plated on the object.

Question 20

What are

two uses of electroplating?

Answer 20

1. Coating cutlery and cooking utensils for protection.
2. Improving the appearance of jewellery by coating it with a metal like gold or silver.

Question 21

What is

sacrificial protection of corrosion?

and how does it work?

Answer 21

this involves placing a more reactive metal with the metal

the water and oxygen react with this ‘sacrificial’ metal instead of the other metal in the object you’re protecting