Chapter 9

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

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

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

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

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

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

. 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

Most important property . High strength . Low density

Most important property . Low density . Good electrical conductor

Most important property . Resistant to corrosion.

Electrical wires . Good electrical conductor . Ductile

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

Mixture of copper and zinc

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

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

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

. 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

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

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

. 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