Transcript increasing reactivity - Thomas Tallis Science

Metal ores and mining
• Ores are naturally occurring rocks found in the
Earth’s crust.
• They contain metal/metal compounds in sufficient
amounts to make it worthwhile extracting them
• Ores are mined and maybe concentrated before the
metal is extracted and purified
increasing reactivity
The reactivity of a metal determines how
it is extracted.
potassium
sodium
calcium
magnesium
aluminium
(carbon)
zinc
iron
lead
(hydrogen)
copper
silver
gold
platinum
Metals above carbon in the
reactivity series must be
extracted using electrolysis.
Electrolysis can also be used
to purify copper.
Metals less reactive than
carbon can be extracted from
their ores by reduction using
carbon, coke or charcoal.
Platinum, gold, silver and
copper can occur native
and do not need to be
extracted.
Reducing iron oxide
• Metals that are less reactive than carbon can be extracted
from their oxides by reduction with carbon
• The metal is reduced because it loses oxygen
• For example, iron oxide is reduced in the blast furnace to
make iron
Electrolysis
• Metals that are more reactive than carbon, such as aluminium, are
extracted by electrolysis of molten compounds.
• The use of large amounts of energy in electrolysis makes these
metals expensive
• Copper can be purified by electrolysis.
• The supply of copper-rich ores is limited and so copper can also be
obtained from solutions of copper salts by electrolysis or by
displacement using scrap iron
Recycling metals
• We should recycle metals because extracting them
uses limited resources and is expensive in terms of
energy and effects on the environment
The elements in the central block of the
periodic table are known as transition metals
(between group 2 and group 3)
group 3
group 2
Here, the word
Sc Ti V Cr Mn Fe Co Ni Cu Zn
‘transition’ is
Y Zr Nb Mo Tc Ru Rh Pd Ag Cd used to mean
‘in-between’.
La Hf Ta W Re Os Ir Pt Au Hg
Ac Rf Db Sg Bh Hs Mt Ds Rg ?
Properties of Transition metals
Like other metals
• They are good conductors of heat and electricity
• They can be bent or hammered into shape
• They are useful as structural materials and for making
things that must allow heat or electricity to pass through
them easily
Metals and their uses
Transition
metals
Uses
Properties
Iron
Alloyed with carbon to
make steel
Brittle by itself, low carbon steel easily
shaped, high carbon steel are harder,
stainless steel resistant to corrosion
Copper
Used for electrical wires
and plumbing
Good conductor of electricity and heat, can
be bent but is hard enough to make pipes
Platinum
Reduces pollution from car
exhausts, jewellery
Very low reactivity. Hard to extract from its
ore as it can’t be reduced, which makes it
expensive.
Titanium
Used to make artificial hip
joints
Low density, resistant to corrosion.
Nickel
Is a catalyst in margarine
production
Speeds up the reaction but does not take
part in it.
Another
important
metal
Uses
Properties
Aluminium
Transport, construction,
packaging
Low density, resistant to corrosion. Hard to
extract from its ore as it can’t be reduced,
which makes it expensive.
- Most metals in everyday use are alloys as pure copper, gold
and aluminium are too soft for most uses
- They are mixed with other similar metals to make them
harder
Impure iron
• Iron from the blast furnace contains about 96% iron.
• The impurities make it brittle and so it has limited uses
Alloys can be designed to have properties
for specific uses
Stainless steel
Low carbon steel
High carbon steel
• Steels are alloys of iron and carbon. Some steels
contain other metals.
• Low carbon steels are easily shaped, high carbon
steels are hard and stainless steels are resistant to
corrosion
Some steels contain other metals.