3.3 Metals

Question 1

Metallic structure

Answer 1

A lattice of positive metal ions
A sea of delocalized electrons

Question 2

Metallic bonding definition

Answer 2

The electrostatic attraction between the positive metal ions and the negative delocalized electrons

Question 3

Strength of metallic bonding

Answer 3

Usually very strong

Question 4

Metal properties (3) and why (in terms of structure)

Answer 4

1. High melting points - because metallic bonding is usually very strong, so lots of energy is needed to break it
2. Conduct electricity - because delocalized electrons are free to move through the lattice and carry charge
3. Malleable - because the layers of metal ions can slide over each other

Question 5

Alloy definition

Answer 5

Mixtures of a metal with one or more other element, usually other metals or carbon

Question 6

Commonly known alloys (3)

Answer 6

Steel
Brass
Bronze

Question 7

Iron use

Answer 7

Making steel - as steel is more useful than iron

Question 8

Low carbon steel use

Answer 8

ships, cars, bridges etc - as it is strong, but due to the low carbon it can be hammered into various shapes

Question 9

High carbon steel use

Answer 9

Tools (e.g. knives, screwdrivers) - as the high carbon means it is less malleable and stiffer than low carbon steel

Question 10

Stainless steel use

Answer 10

Cutlery, cooking utensils, kitchen sinks - as Cr forms oxide layer that resists corrosion, so stays shiny and clean

Question 11

Copper use

Answer 11

wires, cooking pans, water pipes - as it is an excellent conductor of heat and electricity, unreactive and malleable

Question 12

Aluminium use

Answer 12

Aircraft bodies, power cables - as it is low-density, high strength and conducts

Question 13

Order of reactivity (lowest to highest)

Answer 13

Au
Ag
Cu
H
Pb
Fe
Zn
Al
Mg
Ca
Li
Na
K

Question 14

Metal and water reaction equation

Answer 14

Metal + water —> metal hydroxide + hydrogen

Question 15

Reaction between magnesium and water equation

Answer 15

Magnesium + water —> magnesium hydroxide + hydrogen
(Mg + 2H2O —> Mg(OH)2 + H2)

Question 16

Reaction between magnesium and water observations

Answer 16

Effervescence - due to hydrogen gas being produced
Solid disappears - due to being used up in the reaction

Question 17

Displacement reactions

Answer 17

More reactive metals can displace less reactive metals from their compounds

Question 18

Observations to make during displacement reactions

Answer 18

Solid colour change
Solution colour change

Question 19

Acid and metal reactions

Answer 19

Acid + metal —> salt + hydrogen

Question 20

When is a salt formed

Answer 20

It is a compound formed when H is displaced from an acid

Question 21

Observations during acid and metal reaction

Answer 21

Metal disappears as it is used up in the reaction
Fizzing because a gas (hydrogen) is produced

Question 22

How does reactivity affect a metals rate of reaction with an acid

Answer 22

The more reactive a metal is, the faster it will react with an acid

Question 23

What metals can you not react with an acid

Answer 23

Au, Ag, Cu - as it is less reactive than hydrogen so it cannot displace it
Li, Na, K - as its reaction with acids is too violent

Question 24

Test for hydrogen

Answer 24

Lit split
Squeaky pop

Question 25

How are most metals found in the earths crust

Answer 25

Compounds with oxygen and sulphur

Question 26

Why are most metals compounds with oxygen and sulphur

Answer 26

Because those metals have reacted with oxygen and sulphur

Question 27

Name for rocks containing specific metal compounds

Answer 27

Ores

Question 28

What are native metals

Answer 28

Gold and silver They are too unreactive to have combined with oxygen or sulphur They are instead found native, meaning chemically unbonded

Question 29

Do native metals need to be chemically extracted

Answer 29

No - they already exist on their own

Question 30

Two ways in which metals can be extracted from their compounds

Answer 30

1. Using electricity 2. Carbon extraction

Question 31

Using electricity to extract metals from their ores

Answer 31

Metals more reactive than carbon cannot be displaced by carbon so electricity is used to break down their compounds

Question 32

Using carbon extraction to extract metals from their ores

Answer 32

Metals less reactive than carbon can be displaced by carbon by heating it with carbon

Question 33

Reduction definition

Answer 33

Loss of oxygen

Question 34

Oxidation definition

Answer 34

Gain of oxygen

Question 35

Reducing agent definition

Answer 35

Takes oxygen away from something else

Question 36

Oxidising agent definition

Answer 36

Gives oxygen to something else

Question 37

Redox definition

Answer 37

When reduction and oxidation happen in the same reaction

Question 38

Chemical name for rust

Answer 38

Hydrated iron (III) oxide

Question 39

What is rusting

Answer 39

A chemical process by which iron is oxidised to form rust

Question 40

What does rusting require

Answer 40

Water Oxygen

Question 41

3 ways to prevent rusting

Answer 41

Using barriers Sacrificial protection Galvanising

Question 42

How does using barriers prevent rusting

Answer 42

Coat the iron in paint, oil, grease or plastic Prevents iron coming into contact with oxygen or water Only works if the coating is intact - as soon as it breaks, riding happens Oil/grease is better for moving parts, paint or plastic is better for stationary objects (coating material depends on use)

Question 43

How does using sacrificial protection prevent rusting

Answer 43

Attach a block of a more reactive metal (e.g. magnesium) to the iron This works by displacing the iron from rust as soon as the rust forms However, the block of metal has to be replaced often

Question 44

How does using galvanising prevent rusting

Answer 44

This specifically involves coating the iron in zinc It works both ways: coating prevents oxygen and water from coming into contact with iron, but even if a crack appears, zinc is more reactive than iron, so acts as sacrificial protection as well