Reactivity and extraction of metals

Potassium (reacts with water, acid and oxygen)
Sodium (reacts with water, acid and oxygen)
Lithium (reacts with water, acid and oxygen)
Calcium (reacts with water, acid and oxygen)
Magnesium (reacts with acid and oxygen)
Aluminium (reacts with acid and oxygen)
Carbon (reacts with acid and oxygen)
Zinc (reacts with acid and oxygen)
Iron (reacts with acid and oxygen)
Hydrogen (reacts with oxygen)
Copper (reacts with oxygen)
Silver (reacts with oxygen)
Gold (doesn't react)

A few very reactive metals will react with cold water
Products are a metal hydroxide (forming alkaline solution) and hydrogen gas (can see bubbles given off)
eg potassium 2K + 2H2O -> 2KOH + H2

Most metals react with acid
the more reactive the metal, the more hydrogen it will give off
metal + acid -> salt + hydrogen

Almost all metals react with oxygen
metal + oxygen -> metal oxide
only gold does not react with oxygen as it is extremely unreactive

if one metal is more reactive then it will displace a less reactive metal
eg iron would be displaced from iron oxide by aluminium
displacement reactions are redox reactions
can be seen easily with metal salts as more reactive metal gradually disappears as it forms a solution and less reactive metal coats surface of more reactive metal

By what it reacts with (water, oxygen, acid)
By what other metals it displaces

Both air and water are needed for iron to rust
iron + oxygen + water -> hydrated iron (III) oxide

rusting can be prevented by excluding oxygen and water by: painting, coating with plastic, using oil or grease
water can be kept away using a desiccant in the container (absorbs water vapour)
oxygen can be kept away by storing the metal in a vacuum container
sacrificial protection: where the metal you want to be protected from rusting is galvanised with a more reactive metal, which will rust first and prevent water and oxygen reaching the layer underneath (eg zinc is used to galvanise iron)

gain of oxygen OR loss of electrons

loss of oxygen OR gain of electrons

a reaction in which both oxidation and reduction occur

causes another reactant to be oxidised and is reduced itself

causes another reactant to be reduced and is oxidised itself

Most metals are extracted from ores in the Earth's crust
As gold is so unreactive it is found in the Earth as the metal itself
The method used to extract metals from the ore in which they are found depends on their reactivity
The most reactive metals (potassium, sodium, calcium, magnesium, aluminium, carbon) are extracted by electrolysis (other metals can be electrolysed too but because it is so expensive you wouldn't if it can be done more cheaply with carbon)
Metals that are less reactive than carbon can be extracted by reaction with carbon

Aluminium ore is called bauxite
Bauxite is purified to form a white powder, aluminium oxide, from which aluminium can be extracted
Aluminium oxide needs to be made molten so electricity can pass through it
Aluminium oxide has a very high melting pointand would be expensive to melt so it is dissolved in molten cryolite which has a lower melting point
It is then electrolysed in an electrolysis tank where both the anode and cathode are made of graphite
Aluminium forms at the cathode (negative electrode) and sinks to the bottom of the tank, where it is tapped off
Ionic half equation of aluminium: Al3+ + 3e- --> Al
Oxygen forms at the anode (positive electrode)
Ionic half equation of oxygen: 2O2- - 4e- --> O2

Iron oxide loses oxygen, and is therefore reduced. The carbon gains oxygen, and is therefore oxidised.
2Fe2O3(s) + 3C(s) -> 4Fe(l) + 3CO2(g)
For iron, this is carried out at high temperatures in a blast furnace

Phytoextraction
Bacterial extraction

Some bacteria absorb metal compounds
Produce solutions called leachates which contain the metals

Some plants absorb metal compounds through their roots
They concentrate these compounds as a result of this
The plants can be burned to produce an ash that contains the metal compounds

low density
corrosion-resistant
used for aircraft, trains, overhead power cables, saucepans and cooking foil

soft and easily bent
good conductor of electricity
does not react with water
used for electrical wiring and plumbing

from the blast furnace: hard, but too brittle for most uses, so converted to steel
pure iron: too soft for many uses

Low carbon steel: 0.25% carbon, easily shaped, car body panels
High carbon steel: 2.5% carbon, hard, cutting tools
Stainless steel: chromium & nickel, resistant to corrosion, cutlery and sinks

Most metals in everyday uses are alloys. Pure copper, gold, iron and aluminium are all too soft for everyday uses and so are mixed with small amounts of similar metals to make them harder for everyday use
eg Gold in jewellery is usually an alloy with silver, copper and zinc

In a pure metal, the ions are all the same size and are in a regular arrangement of layers, meaning that they can slide over each other easily, making them soft
In an alloy, there are different sized ions, which disrupts the regular arrangement and prevents layers being able to slide over each other so easily