Chapter 9

Question 1

Propertiesnof metals (the properties of metals are due to metallic bonding)

Answer 1

• conduct heat and electricity
• malleable (can be hammered and made into different shapes) + ductile (can be drawn into wires)
• High-density + high melting points

Question 2

Properties of non metals

Answer 2

• Don’t conduct heat and electricty
• Brittle when solid
• Low melting points

Question 3

Chemical properties of metals -> reactivity with cold water

Answer 3

reactivity with cold water: forms metal hydroxide and hydrogen gas
. Includes: metals above and including magnesium -> metals like potassium, sodium and calcium react vigorously with water

Question 4

Chemical properties of metals -> reactivity with steam

Answer 4

Reactivity with steam: forms of metal oxide and hydrogen -> more reactive metal = faster reaction
. Includes: metals under magnesium and above, including iron

Question 5

Chemical properties of metals -> reactivity with dilute acid

Answer 5

Reactivity with dilute acid: forms, salt and hydrogen gas -> more reactive metal = faster reaction with acid
. Includes: metals above copper

Question 6

Chemical properties of metals -> reactivity with oxygen

Answer 6

Reactivity with oxygen: forms a metal oxide
. Includes: metals above, and including copper

Question 7

Chemical properties of metals -> aluminium

Answer 7

. Aluminium: doesn’t react with water or dilute acids -> surface of aluminium reacts with oxygen in air to form a layer of unreactive aluminium oxide which acts as a barrier against further oxidation

Question 8

Uses of metals: aluminium -> aircraft manufacture

Answer 8

Most important property
. High strength
. Low density

Question 9

Uses of metals: aluminium -> overhead power cables manufacture

Answer 9

Most important property
. Low density
. Good electrical conductor

Question 10

Uses of metals: aluminium -> food containers

Answer 10

Most important property
. Resistant to corrosion.

Question 11

Uses of metals: copper

Answer 11

Electrical wires
. Good electrical conductor
. Ductile

Question 12

Alloys

Answer 12

Alloys: mixture of a metal with other element -> can be harder and stronger than pure metals + more useful
-> alloys contains atom of different sizes, distorting the normal regular arrangement of atoms in metals -> harder for layers to slide over each other

Question 13

Common alloys: brass

Answer 13

Mixture of copper and zinc

Question 14

Common alloys: stainless steel

Answer 14

Mixture of iron and other elements (nickel, chromium and carbon) -> used in cutlery due to its hardness and resistance to resting

Question 15

Displacement reactions

Answer 15

More reactive metals displace less reactive metals -> reactive metals easily lose electrons to form cations (less reactive metals don’t give up electrons to form cations as easily)
. Reactive metal = reducing agent

Question 16

Corrosion of metals: corrosion of iron and steel

Answer 16

. Iron and steel corrode easily to make rust (hydrated iron (III) oxide) -> only happens in the presence of both oxygen and water

Question 17

Corrosion of metals: corrosion of iron and steel -> preventing rusting of iron

Answer 17

. Barrier methods: prevent rusting by excluding oxygen or water
- Painting
- Greasing
- Coating with plastic
. Sacrificial protection: placing a more reactive metal with iron -> water and oxygen react with this sacrificial metal instead of with iron as it loses electrons more easily than iron to form cations
-> zinc: often used in sacrificial protection -> coating of zinc is called galvanizing

Question 18

Extraction of metals

Answer 18

Extraction of metals from its ore (metal oxide) always involves the reduction of the metal
. More reactive metal = harder to extract from or ore
- reduction with carbon: heating or with carbon or carbon monoxide

Question 19

Extraction of iron

Answer 19

. Iron ore: Hematite
. The blast furnace -> reduction by carbon

Question 20

Extraction of aluminium by electrolysis

Answer 20

. Aluminium ore: bauxite
. Aluminium oxide is dissolved in molten cryolite -> lower is melting point (less energy -> reduces cost) + increases electrical conductivity
-> anode needs to be replaced regularly as oxygen reacts with the graphite anodes (carbon) to produce carbon dioxide due to high temperatures -> anode erodes + shrinks