Metals Flashcards

1
Q

(Metal) atoms are closely packed and arranged in orderly layers of (__) atoms. The layers of (__) atoms can slide over each other easily.

Hence (metal) is __________ (property)?

A

Hence (metal) is malleable and can be beaten into shape without breaking.

Hence (metal) is ductile and can be pulled into wires without breaking.

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2
Q

(Metal) atoms are closely packed and arranged in orderly layers of (__) atoms.

Hence (metal) has __________ (property)?

A

Hence (metal) has a high density since the mass of (__) atoms per unit volume is high.

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3
Q

Why do metals have high melting and boiling points?

A

Metals have a metallic structure with strong metallic bonds between the (__) ions and the sea of delocalised electrons. A lot of energy is needed to break these bonds. Hence (__) has a high melting and boiling point.

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4
Q

Why can metals conduct heat and electricity?

A

Metals have a metallic structure with strong metallic bonds between the (__) ions and the sea of delocalised electrons.

The mobile electrons can easily collide with other particles, making heat transfer efficient.
OR
The mobile electrons are able to act as charge carriers to conduct electricity.

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5
Q

Alloys are weaker than their constituent metals. True or false?

A

False. They are stronger.

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6
Q

Alloys are harder than their constituent metals. True or false?

A

True. They are less malleable because they are stronger.

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7
Q

What makes alloys harder than their constituent metals?

A

In an alloy, the atoms of the different metals / elements have different atomic radii. The (smaller percentage / non metal element) atoms disrupt the orderly arrangement of the layers of (main metal) atoms.

The atoms of different sizes cannot slide over each other easily when a force is applied. Hence, the alloy is stronger than (pure metal).

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8
Q

Where is aluminium in the reactivity list?

A

Below Magnesium, above Zinc

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9
Q

Why does aluminium sometimes behave like the unreactive metals?

A

There is a protective layer of aluminium oxide that naturally coats the metal.

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10
Q

Is Tin or Zinc more reactive?

A

Zinc

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11
Q

Does copper react with oxygen?

A

Yes

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12
Q

Which metals can react with cold water?

A

Potassium, Sodium, Calcium, Magnesium (very slowly)

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13
Q

Which metals can react with water?

A

K - Mg: Cold water (produce hydroxide)
Mg - Fe: Steam (produce oxide)

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14
Q

Which metals react with Oxygen?

A

K - Hg

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15
Q

Which metals react with acid?

A

K - Pb

for tin and lead, they react very slowly

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16
Q

More reactive metals form more/less stable ions?

A

More stable ions

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17
Q

Will the ions of more reactive metals react / decompose more easily?

A

No. They are more stable, so they react / decompose less easily.

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18
Q

Less reactive metals form more/less stable ions?

A

Less stable ions.

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19
Q

Will less stable ions react / decompose more easily?

A

Yes

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20
Q

What is a metal displacement reaction?

A

A reaction where a more reactive metal displaces the ions of a less reactive metal from its aqueous salt.

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21
Q

Why do metal displacement reactions happen?

A

A more reactive metal has a higher tendency to lose its valence electrons to form a more stable ion. Hence it will donate its electrons to the metal ions of the less reactive metal.

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22
Q

Why is a more reactive metal a stronger reducing agent?

A

A reducing agent donates electrons to other substances. Since a more reactive metal has a higher tendency to lose electrons than a less reactive metal, it is a stronger reducing agent.

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23
Q

What is a thermite reaction?

A

A type of metal displacement reaction where the more reactive metal displaces the ions of the less reactive metal from its solid metal oxide.

A lot of heat is generated in the process. (energy needed to break bonds < energy given out when bonds are formed)

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24
Q

What is an application of a thermite reaction?

A

Melt railways tracks to mend broken tracks.

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25
Q

What is an example of thermite reaction?

A

2Al (s) + Fe2O3 (s) –> Al2O3 (s) + 2Fe (s)

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26
Q

The more stable the element, the less stable the compound. True or false?

A

False. The more stable the element, the more stable the compound.

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27
Q

Why do the Hg-Pt oxides decompose on heating but not the other oxides?

A

Mercury, Silver, Gold and Platinum are less reactive than the rest of the metals in the reactivity series. The ionic bonds in the oxides of Hg-Pt are not as strong as that in the more reactive metals. Hence, they are less stable and are more likely to decompose on heating.

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28
Q

Very stable ions form unstable or stable compounds?

A

Stable (strong ionic bonds within the compound)

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29
Q

The oxides of Potassium to Aluminium are not reduced by hydrogen and carbon. Why?

A

K-Al are very reactive metals that lose valence e- readily to form stable ions. These ions form compounds with a strong ionic bond that cannot be broken by hydrogen and carbon. Hydrogen and carbon are not reactive enough to reduce the metal ions to metal atoms.

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30
Q

For metal oxides, which ones will decompose on heating?

A

Hg - Pt

Give metal and oxygen.

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31
Q

Does every metal have a metal oxide?

A

Yes

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32
Q

What is the action of hydrogen on metal oxides?

A

For K-Zn, no reaction
For Fe-Pt, reduced to metal

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33
Q

What is the action of carbon on metal oxides?

A

For K-Al, no reaction
For Zn-Pt, reduced to metal

34
Q

Which oxides react with water to form hydroxides?

A

K - Ca (same as those elements that will react with cold water)

35
Q

Will Mg-Pt oxides react with water?

A

No. They will become precipitates because they are insoluble.

36
Q

The less reactive the metal ion, the higher or lower the tendency to be reduced back to its metal atom?

A

Higher.

Because these ions are less stable, so they are very reactive and will react to form atoms again.

37
Q

Metal hydroxides only exist for which metals?

A

K - Cu

38
Q

Metal Carbonates only exist for which metals?

A

K - Cu

39
Q

For hydroxides, what will happen when heated?

A

K & Na: No reaction
Ca-Cu: Decompose to give metal oxide and water

40
Q

For carbonates, what will happen when heated?

A

K & Na: No reaction
Ca-Cu: Decompose to give metal oxide and carbon dioxide.

(for Ca-Cu oxides, further heating will not decompose it. only Hg-Pt oxides decompose on heating)

41
Q

Do all metals have nitrates?

A

Yes

42
Q

Action of heat on nitrates?

A

K & Na: Decompose to give metal nitrite and oxygen

Ca-Cu: decompose to give metal oxide, nitrogen dioxide and oxygen

Hg-Pt: decompose to give metal, oxygen and nitrogen dioxide

43
Q

What are metal elements that react with cold water and what products do they produce?

A

K, Na, Ca, Mg (very slowly)

They produce metal hydroxide and hydrogen

44
Q

What are metal elements that react with steam and what products do they produce?

A

Mg, Al, Zn, Fe

They produce metal oxide and hydrogen

45
Q

Describe how magnesium reacts with steam and water.

A

It reacts with steam with a dazzling white light but reacts very slowly with cold water

46
Q

List the observations of the reactions between water and K, Na, Ca, Mg.

A

K: reacts very violently with cold water

Na: reacts violently with cold water

Ca: reacts with cold water

Mg: reacts very slowly with cold water, but reacts with steam with a dazzling white light

47
Q

Water reacts with metal until which element? which element?

A

Fe

48
Q

Describe the reaction of acids with K, Na, Ca, Mg

A

K: Reacts very explosively

Na: Reacts explosively

Ca: Reacts very vigorously

Mg: Reacts vigorously

49
Q

Acids reacts with metal until which element?

A

Pb

but for Sn and Pb, very slow reaction

50
Q

Which metals need to undergo electrolysis to be extracted?

A

Na - Al

Because these metals are more reactive than carbon so they their ionic bonds are too strong to be broken by carbon atoms.

51
Q

Which metals are found naturally uncombined as elements?

A

Ag - Pt

(below Hg, because metal reacts with oxygen until Hg. so Ag-Pt do not get oxidised that easily naturally)

52
Q

Which metals are found as compounds naturally and can be extracted by blast furnace?

A

Zn-Hg

53
Q

What kinds of compounds do the medium reactive metals form and how to extract the metal from their compounds?

A

They form metal sulfates and metal oxides.

For metal sulfates, heat until they decompose into metal oxides + SO2

Heat the metal oxides with carbon in a blast furnace.

54
Q

What is the name of iron ore and what does it contain?

A

Haematite

contains Iron III Oxide

55
Q

What is the name of aluminium ore?

A

Bauxite

contains Al2O3

56
Q

What is the name of tin ore?

A

Cassiterite

SnO2

57
Q

What is the name of lead ore?

A

Galena

PbS (Lead II Sulfide)

58
Q

What is the name of zinc ore?

A

Sphalerite

ZnS (Zinc sulfite)

59
Q

Which transition metals have only 1 oxidation number?

A

Aluminium, Zinc, Cadmium

Oxidation state of +2

60
Q

List the raw materials used for blast furnace extraction

A
  1. Metal ore (usually haematite to extract Iron)
  2. Coke (contains carbon, the main reducing agent)
  3. Limestone (contains CaCO3 to remove impurities)
  4. Hot air (provide oxygen for combustion)
61
Q

How does limestone remove impurities in blast furnace extraction?

A

The calcium carbonate in limestone decompose on heating to form Calcium Oxide + CO2. Calcium oxide reacts with impurities like silicon dioxide to form calcium silicate CaSiO3 (slag)

62
Q

List the waste gases evolved from a blast furnace.

A
  1. Nitrogen (naturally in air)
  2. Carbon monoxide
  3. Carbon dioxide
  4. Sulfur dioxide (sulfur may be present in ore)
  5. Oxides of nitrogen (side product, bcos N combined with O on heating)
63
Q

What’s the temperature inside the blast furnace?

A

Highest 2000degC (at the area where hot air enters)

Temperature decreases as the hot air rises, to about 800degC at the top opening.

64
Q

List the steps of iron extraction in a blast furnace.

A
  1. coke reacts with oxygen from hot air

C + O2 –> CO2

  1. carbon dioxide reacts with even more coke

CO2 + C –> 2CO

  1. Carbon monoxide reacts with Fe2O3 in haematite to give iron and carbon dioxide

3CO + Fe2O3 –> 2Fe + 3CO2

  1. The calcium carbonate in limestone decomposes on heating to form calcium oxide and carbon dioxide.

CaCo3 –> CaO + Co2

  1. Calcium oxide reacts with silicon dioxide to form Calcium Silicate (slag).

CaO + SiO2 –> CaSiO3

65
Q

Does slag float or sink above/below pig iron in blast furnace?

A

Float

66
Q

What comes out of the blast furnace?

A
  1. Molten slag (calcium silicate)
  2. Molten iron (pig/cast iron)
  3. Waste gases
67
Q

How to make steel from cast iron?

A
  1. Oxygen is blown into the molten iron to react with any leftover impurities like sulfur and phosphorus. The gaseous oxides formed are then blown out.
  2. Carbon and other elements are added to the molten iron to form different types of steel.
68
Q

Why do we desire steel instead of iron?

A

Steel is harder and stronger.

69
Q

What are the uses of iron?

A

Make iron pots and pans.
Make bridges.
Make steel gates.

70
Q

Advantages of iron?

A
  1. Relatively easy to bend and shape using simple tools.
  2. Iron is heat resistant so it can be used to make engines.
  3. Iron can be magnetised so it can be used in electricity generators.
  4. Iron is plentiful, will not run out easily.
71
Q

List the types of steel.

A
  1. High carbon steel (more carbon added): Very strong, used to make tools
  2. Mild steel (less carbon added): More malleable, used to make transport vehicles.
  3. High speed steel (tungsten added): Stays hard and strong at high temperatures, used to cut things at high speed
  4. Stainless steel (chromium and nickel added): No rust, make cutlery and medical instruments
  5. Chromium steel (chromium added): Very hard
72
Q

What is rusting?

A

The corrosion of iron and steel.

73
Q

Conditions needed for rusting?

A
  1. Presence of steel
  2. Water
  3. Oxygen

(rust is Fe2O3 . xH2O)

74
Q

What are the 2 types of rusting protection?

A
  1. Surface protection / barrier protection
  2. Sacrificial protection

(or just use stainless steel)

75
Q

What is surface protection?

A

A coat of paint, oil/grease, plastic or metal (less reactive) is coated on the surface of the iron / steel. This stops air and water from reaching the iron / steel.

76
Q

What is sacrificial protection?

A

Attaching a more reactive metal to corrode in place of iron. The more reactive metal is sacrificed.

77
Q

What are some examples of sacrificial protection?

A
  1. Galvanised iron (iron coated with zinc)
  2. Protecting ships using zinc blocks
  3. Protecting underground steel pipes using magnesium blocks.
78
Q

How does sacrificial protection work?

A

A more reactive metal loses electrons more readily than a less reactive ion.

Since Zn/Mg is more reactive than iron, electrons flow from Zn/Mg to to iron, causing Zn/Mg to corrode more easily and preventing iron from rusting.

The Zn/Mg undergoes sacrificial protection and corrodes in place of Iron.

79
Q

In sacrificial protection, does the more reactive metal have to fully coat the iron?

A

No. It just needs to be in contact via a conductor (eg, wire).

80
Q
A