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objectivesobjectives
• What are metals? Names of common metals
• Uses and why• Extraction methods• Problems
19/04/23
MetalsMetals
• Most of the periodic table is made of metals, about 3 quarters
• Group 1 and group 2 reactive metals, transition metals and the poor metals
19/04/23
Where are the transition Where are the transition metals?metals?
The transition metals are the block of elements located between group 2 and group 3 of the periodic table.
Ac Rf Db Sg Bh Hs Mt Ds Rg
La Hf Ta W Re Os Ir Pt Au Hg
Y Zr Nb Mo
Tc Ru Rh Pd Ag Cd
Sc Ti V Cr Mn
Fe Co Ni Cu Zn
?
Here, the word ‘transition’ is used to mean ‘in-between’.
group 2 group 3
The transition metals are known as ‘typical’ metals because of their physical properties. They are:
What are the properties of the transition What are the properties of the transition metals?metals?
lustrous (bright and shiny).
high density.
good conductors of heat and electricity.
high melting and boiling points (except mercury, which is liquid at room temperature).
hard and strong.
malleable (can be bent and pressed into different shapes) and ductile (can be drawn into wires).
structurestructure
• Free electrons allow metals to conduct heat and electricity
• Forms giant structures• In layers-so easy to slide over each
other. Bendy/malleable
19/04/23
19/04/23
The Transition MetalsThe Transition Metals
1) This section includes metals like gold, mercury, iron, copper
Some facts…
2) They are all ______ and solid (except _________)
3) They are ____ reactive than the alkali metals
Words – hard, coloured, mercury, less, catalyst, insoluble
4) They can form __________ compounds, usually _______
5) They can be used as a ______ (a chemical that speeds up a reaction)
Comparing properties of Comparing properties of different metalsdifferent metals
are more dense. This means that in a fixed volume of metal there are more atoms of a transition metal than there are of an alkali metal.
have higher melting and boiling points – except mercury.
are harder and stronger. They cannot be cut with a knife.
Compared to the alkali metals, the transition metals:
How reactive are the How reactive are the transition metals?transition metals?
The transition metals are much less reactive than the alkali metals.
They tend to react relatively slowly, for example with air, water and acid.
Copper does not react with water whereas the alkali metals, such as sodium, react vigorously.
Copper does not burn in air whereas the alkali metals, such as sodium, burn vigorously.
How reactive are the How reactive are the transition metals?transition metals?
The general trend is for a decrease in reactivity from left to right across the periodic table. There are exceptions, such as zinc which is more reactive than expected.
Sc Ti V Cr Mn
Fe Co Ni Cu Zn
decrease in reactivity
Another exception is iron, which does react quite readily with air and water causing rust.
Zinc is more reactive than expected.
What is the chemical name of rust?
What happens to iron when What happens to iron when it rusts?it rusts?
Rusting is an oxidation reaction between iron, oxygen and water, which leads to the formation of hydrated iron (III) oxide - the chemical name for rust.
What are the word and chemical equations for the formation of rust?
water
oxygen
hydrated iron (III) oxide (rust)
iron
+ +
4Fe
(s)2H2O
(g)2Fe2O3.H2O+ 3O2
(g)+
Rusting is a type of corrosion.
19/04/23
RustingRustingRust is formed when iron reacts with water AND _____.
It’s an example of an oxidation reaction which can be sped up using _____. There are several ways of dealing with rust:
1) Regular _______ or oiling
2) Galvanising – this is when iron objects are coated with ______
3) Making objects out of a non-rusting metal, such as ________ _______
4) Attaching zinc bars to ships – the water will react with the zinc before it reacts with the iron, because zinc is more ______
Words – stainless steel, reactive, painting, oxygen, salt, zinc
Transition metal Transition metal compoundscompounds
The number in brackets indicates how many electrons have been lost.
As most transition metals can form different ions, this means they can form multiple compounds.
Copper can form Cu+, which can make the red compound copper (I) oxide – Cu2O.
Copper can also form Cu2+, which can make the black compound copper (II) oxide – CuO.
Transition metal Transition metal compounds and colourcompounds and colour
Most transition metals form coloured compounds.
Copper (II) sulfate crystals (CuSO4.H2O) is blue – these can be turned white by heating the crystals to remove the water.
Iron (III) oxide (Fe2O3) is red/brown – when hydrated this is rust.
Iron (II) oxide (FeO2) is black.
For example:
Uses of coloured tm Uses of coloured tm compoundscompounds
The coloured compounds of transition metals can also be used in many ways, for example:
as coloured glazes on pottery.
to colour paints
to colour stained glass windows
The colour of many gemstones comes from the presence of transition metal compounds. For example, the gemstone jade contains iron.
How are transition metal ions How are transition metal ions identified?identified?
The presence of transition metal ions in a solution can be tested by adding sodium hydroxide solution.If transition metal ions are present, a metal hydroxide is formed. This is insoluble and so appears as a solid called a precipitate.
Cu2+ ions produce a blue precipitate of Cu(OH)2 .
Fe2+ ions produce a grey/green precipitate of Fe(OH)2 . Fe3+ ions produce an
orange/brown precipitate of Fe(OH)3
.
Different metal ions produce different coloured precipitates:
What is thermal What is thermal decomposition?decomposition?
Compounds of transition metals can be broken down into simpler substances by heating them.
For example, carbonates of transition metals are broken down into metal oxides and carbon dioxide when heated.
metal oxide
metal carbonate
+ carbon dioxidehea
t
How can the presence of carbon dioxide be tested?
This is called thermal decomposition.
The reactants and products are different colours.
The gas produced can be bubbled through limewater. If the gas is CO2, it will turn the limewater cloudy.
19/04/23Reactions of metals with Reactions of metals with oxygenoxygen
When a metal reacts with oxygen it will form a METAL OXIDE. This is what happens when a metal rusts. We can make this reaction happen quicker by burning the metal.
METAL + OXYGEN METAL OXIDE
Copy and complete the following reactions:
1) Magnesium + oxygen
2) Copper + oxygen
3) Calcium + oxygen
4) Iron + oxygen
Magnesium oxide
Copper oxide
Calcium oxide
Iron oxide
19/04/23
Reactions of metals with waterReactions of metals with waterWhen a metal reacts with water hydrogen is always given off. The other product will be either a metal hydroxide or a metal oxide.
Copy and complete the following reactions:
1) Sodium + water
2) Potassium + water
3) Calcium + water
4) Iron + steam
METAL + WATER METAL HYDROXIDE + HYDROGEN
METAL + WATER (vapour) METAL OXIDE + HYDROGEN
Sodium hydroxide + hydrogenPotassium hydroxide + hydrogenCalcium hydroxide + hydrogenIron oxide + hydrogen
19/04/23Reactions of metals with Reactions of metals with acidsacids
When a metal reacts with an acid it gives off hydrogen (which can be “popped” using a lit splint). The other product is a salt.
Copy and complete the following reactions:
1) Calcium + hydrochloric acid
2) Zinc + hydrochloric acid
3) Iron + hydrochloric acid
4) Lithium + sulphuric acid
METAL + ACID SALT + HYDROGEN
e.g. magnesium + hydrochloric acid magnesium chloride + hydrogen
Calcium chloride + hydrogenZinc chloride + hydrogenIron chloride + hydrogenLithium sulphate + hydrogen
19/04/23
Complete the following reactions:Complete the following reactions:
1) Lithium + water
2) Lithium + hydrochloric acid
3) Silver + oxygen
4) Magnesium + sulphuric acid
5) Potassium + oxygen
6) Aluminium + oxygen
7) Manganese + water
8) Sodium + sulphuric acid
9) Lithium + oxygen
10)Nickel + hydrochloric acid
Lithium hydroxide + hydrogen
Lithium chloride + hydrogen
Silver oxide
Magnesium sulphate + hydrogen
Potassium oxide
Aluminium oxide
Manganese oxide + hydrogen
Sodium sulphate + hydrogen
Lithium oxide
Nickel chloride + hydrogen
19/04/23
The Reactivity SeriesThe Reactivity Series
The Reactivity Series lists metals in order of reactivity:
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Lead
Copper
Silver
Gold
19/04/23
Displacement reactionsDisplacement reactions
SO4Cu
Copper sulphate
The magnesium DISPLACES the copper from copper sulphate
SO4Mg
Magnesium sulphate
Cu
Copper
A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound.
Magnesium + copper sulphate magnesium sulphate + copper
Mg
Magnesium
19/04/23
Displacement reactionsDisplacement reactions
SO4Cu
Copper sulphate
The magnesium DISPLACES the copper from copper sulphate
SO4Mg
Magnesium sulphate
Cu
Copper
A displacement reaction is one where a MORE REACTIVE metal will DISPLACE a LESS REACTIVE metal from a compound.
Magnesium + copper sulphate magnesium sulphate + copper
Mg
Magnesium
19/04/23
Extracting MetalsExtracting Metals
A METAL ORE is a mineral or mixture of minerals from which it is “economically viable” to extract some metal.
To “extract” a metal from a metal oxide we need to REDUCE the oxygen. This is called a REDUCTION reaction. To put it simply:
Most ores contain METAL OXIDES (e.g. rust = iron oxide).
Some definitions:
Iron OxideIron ore
“Reduce” the oxygen to make
iron
19/04/23How do we do it?How do we do it?Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS
Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE
These LOW REACTIVITY metals blatantly won’t need to be extracted because they are SO unreactive you’ll find them on their own, not in a metal oxide
19/04/23
The Blast FurnaceThe Blast Furnace1) HAEMATITE (iron ore), limestone and coke (carbon) are fed in here
2) Hot air is blasted in here
3) The carbon reacts with oxygen from the air to form carbon dioxide.
4) The carbon dioxide reacts with more carbon to form carbon monoxide
6) Molten slag (waste) is tapped off here
5) Carbon monoxide reduces iron oxide to iron. The molten iron is tapped off here
Iron oxide + carbon monoxide iron + carbon dioxide
19/04/23
ElectrolysisElectrolysis
Solid copper chloride ions
Solid copper chloride ions after being dissolved
Chloride ion
Copper ion
2
2
19/04/23
ElectrolysisElectrolysis
++++
----
Positive electrode
Cu2+
Cu2+
Cu2+
Negative electrode
Cl-
Cl-
Cl-
Solution containing copper and
chloride ions
19/04/23
ElectrolysisElectrolysisElectrolysis is used to extract a HIGHLY REACTIVE metal.
= chloride ion
= copper ion
When we electrolysed copper chloride the
negative chloride ions moved to the positive
electrode and the positive copper ions
moved to the negative electrode – OPPOSITES
ATTRACT!!!
19/04/23Redox reactionsRedox reactionsThese happen during electrolysis:
These two processes are called REDOX REACTIONS
OILRIG – Oxidation Is Loss of electrons
Reduction Is Gain of electrons
At the positive electrode the negative ions LOSE electrons to
become neutral – this is OXIDATION
At the negative electrode the positive ions GAIN electrons to
become neutral – this is REDUCTION
19/04/23
Purifying Purifying AluminiuAluminiu
mm
Aluminium has to be extracted from its ore (called ________) by electrolysis. This is because aluminium is very ___________. The ore is mixed with cryolite to lower its ________ ________. The ore is then melted so that the ions can ______. The positively charged aluminium ions gather at the ___________ electrode. Oxygen forms at the positive electrode and causes it to wear away, which means that they have to be __________ frequently.
Words – melting point, replaced, negative, bauxite, reactive, move
19/04/23
Purifying CopperPurifying Copper
++++
----
Solution containing copper ions
(copper sulphate)
Impure copper
Cu2+
Cu2+
Cu2+
Pure copper
At the positive electrode:
Cu(s) Cu2+(aq) + 2e-
At the negative electrode:
Cu2+(aq) + 2e- Cu(s)
19/04/23
Using IronUsing IronIron produced by the blast furnace (“cast iron”) contains about 96% iron and 4% impurities. These impurities make it very brittle and easy to break.
Ironbridge, Shropshire – made out of cast iron and safe for horses and carts but not modern vehicles.
19/04/23
Using IronUsing IronIn pure iron all impurities are removed. This makes the iron soft:
Adding 1% impurities makes the iron much stronger:
19/04/23
Making steelMaking steel
Amount of carbon added (%)0.5% 1%
Strong
Weak
1.5%
Strength
Hardness
Steel with a low carbon content is easily shaped
Steel with a high carbon content is strong but brittle
Steel with chromium and nickel is called stainless steel
19/04/23
AlloysAlloysSteel is an “alloy” – i.e. a mixture of metals. Here are other alloys:
Gold mixed with copper
Aluminium mixed with magnesium and copper
Aluminiun mixed with chromium