Metals Flashcards
What is the reactivity series
Potassium Sodium Lithium Calcium Magnesium Aluminium (Carbon) Zinc Iron lead (Hydrogen) Copper Silver Gold
How is the reactivity series ordered
Most Reactive –> Least Reactive
What do metals lose when react with other substances
metal atoms lose electrons to form positive ions
How does the reactivity of a metal affect its reactions
More vigorous reactions and more easily it loses electrons it reactions to form positive ions
What happens if a metal higher on the reactivity series reacts with a metal lower than it
A metal higher on the reactivity series can displace a less reactive metal from its compounds
How stable is a reactive metal’s compound
The more reactive a metal the more stable its compounds as the bonds holding it together are very strong
What is the equation for when metal reacts with water
Metal + water –> metal hydroxide + hydrogen
Write the reaction of sodium and water
Sodium + water → sodium hydroxide + hydrogen
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
With what metals does water react with
all the metals above zinc
What happens when a metal reacts with an acid
• Metal + acid –> salt + hydrogen (g)
redox reaction as metal is being oxidised and hydrogen reduced
What metals react with acids
all above hydrogen except zinc and iron usually slowly
How do you test for presence of hydrogen gas
Lit splint in test tube should make squeaky pop noise
When is hydrogen produced in metals reactions
Always made when a metal reacts with water or a dilute acid
How do metals react with oxygen
Metal + Oxygen Metal oxide
oxidation reaction
Define oxidation
gain of oxygen and loss of electrons
Define reduction
loss of oxygen and gain of electrons
What is a pneumonic for remembering oxidation and reduction
OILRIG
Oxidation Is Loss
Reduction Is Gain
What are some examples of redox ractions
electrolysis reactions and displacement reactions
What are displacement reactions
A displacement reaction is when a more reactive metal replaces a less reactive metal in a compound.
Where is carbon in the reactivity series
Above zinc
Where is hydrogen in the reactivity series
Above copper
What is a pneumonic to remember the reactivity series
Please Send Charlies Monkeys And Zebras In Large Cages Securely Guarded
Potassium Sodium Calcium Magnesium Aluminium (Carbon) Zinc Iron lead (Hydrogen) Copper Silver Gold
What is an ionic equation
An equation where you have taken the spectator ions out
What are spectator ions
ions that are on both sides of the equation and do not contribute to the reaction
Here is an example of a redox displacement reaction
A balanced equation for the reaction between magnesium and copper sulphate solution can be written in terms of the ions with spectator ions taken out:
Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)
This equation is an example of a balanced ionic equation. It can be split into two half equations:
Mg(s) → Mg2+(aq) + 2e- (oxidation)
Cu2+(aq) + 2e- → Cu(s) (reduction)
Notice that:
• magnesium atoms lose electrons - they are oxidised
• copper ions gain electrons - they are reduced
• Also notice that no electrons disappear or are made they are always balanced or transferred
What are the steps for a half equation
- Write down the reactant and the product.
- Balance the atoms.
- Write the total charge underneath each species in the equation.
- Balance the charge by adding electrons.
What form are most metals found in
Combined with other elements to form compounds (ores)
Define an ore
a rock that contains enough of a metal to make extracting the metal worthwhilr
How does the reactivity of metals determine the method of extraction
- Metals above carbon must be extracted during electrolysis
- Metals below carbon must be extracted from the ore by reduction using carbon,coke or charcoal
What is special about gold or silver
They are native but chemical reactions may be needed to remove elements that might contaminate it
How is iron extracted
- Iron (III) oxide is reduced to molten iron when it reacts with carbon. One of the products is carbon monoxide:
- iron (III) oxide + carbon → iron + carbon monoxide
- Fe2O3(s) + 3C(s) → 2Fe(l) + 3CO(g)
Why is heating a metal with carbon preferred to electrolysis
It is much cheaper than using electrolysis
How is aluminium extracted
extracted from bauxite :
2Al2O3 –> 4Al + 3O2
What happens at the positive anode in electrolysis of aluminium
- O2 ions are oxidised: 2O2- 2O2- + 4e-
- Oxygen reacts with carbon electrodes to form CO2 gas
What happens at the negative electrode in electrolysis of aluminium
- Al3+ gains 3 electrons as it is reduced:
- Al3+ + 3e- –> Al
How is copper oxide extracted
By heating it with carbon it is reduced:
Copper oxide + carbon → copper + carbon dioxide
What is phytomining
• Plants absorb metal ions through their roots the plants are then burnt to produce ash which contains a reasonable concentration of copper in it
What are the steps for phytomining
1) Plants are used to absorb metal compounds such as copper(II) compounds
2. The plants are harvested, then burned to produce ash, which contains the metal compounds
3. An acid is added to the ash to produce a solution containing dissolved metal compounds (leachate)
4. Copper can be obtained from these solutions by displacement using scrap iron
What is bioleaching
extraction of copper using bactera by producing acidic leachate solutions that contain the metal compounds that are desired
What are the advantages and disadvantages of bioleaching
- cheap and simple
- eco-friendly
- can be used on low quality ores
- doesnt need high temp.
- very slow compared to smelting
- toxic chemicals produced
- efficiency is very low; lots of waste
How is the leachate purified
using scrap iron it displaces copper (cost-effective)
iron + copper(II) sulfate → iron(II) sulfate + copper
How is copper purified
Copper is purified by electrolysis, electricity is passed through solutions containing copper compounds
What are the anode and cathode made of in purification of copper
anode is made from impure copper
cathode is made from pure copper
What happens to the anode and cathode in purification of copper
The anode loses mass as copper dissolves and the cathode gains mass as copper is deposited
What are the half equations of the purification of copper
anode: Cu → Cu2+ + 2e- (oxidation)
cathode: Cu2+ + 2e- → Cu (reduction)
Define an alloy
a mixture (a substance containing elements that aren’t chemically bonded) of a metal and other elements
What are softer alloys or pure elements
generally pure elements
Why are pure elements generally softer
As pure metals are ordered in positive regular lattices that can easily deform due to layers passing over each other
Why are alloys harder than pure elements
- Different sized particles
- Lattice structure is disrupted
- So fewer regular layers
What are memory shape alloys
an alloy that when bended can still go back to its original shape
Name 8 well known alloys and the elements they are made up of
- High – Carbon steel : Fe, C (more brittle/ strong)
- Low – Carbon Steel : Fe, C (less brittle/ strong)
- Stainless Steel : Fe, Cr, Ni (resists corrosion)
- Bronze : Cu, Sn
- Solder: Sn, Pb
- Brass: Cu , Zn
- Jewellery Gold : Au, Cu , Zn
- Stirling Silver: Ag , Zn
Name the different alloys of Gold
- 24 Karat Gold. 100% Gold
- 18 Karat Gold. 75% Gold
- 12 Kt. Gold 50% Gold
- 6 Kt. Gold 25% Gold
Define metallic bonding
Metallic Bonding is ‘the electrostatic attraction between a lattice of positive ions surrounded by delocalised electrons
due to the sharing of delocalised electrons
Why do metals conduct electricity
electron cloud is mobile so electrons move freely
Why are metals malleable (can be hammered or bent into shape)
this is due to the regular layers being able to slip over each other
What happens to metals when they are melted
the forces between the metal cations and the delocalised electrons must be broken
Why do metals have very high melting points
strong electrostatic forces of attraction need to be broken which require a lot of energy
Define ductile
can be drawn into wires
What is the opposite of malleable
brittle
What is rusting
Type of corrosion; oxidation between only iron, oxygen and water
What is the equation for rusting
4Fe(s) + 3O2 (g) + 2H2O (g) 2Fe2O3 + H2O
iron + oxygen + water –> Hydrated Iron (III) Oxide
(orange brown substance seen on surface of rusty objects)
Define corrosion
destruction of materials by chemical reactions with substances in the environment, typically oxygen
How can corrosion be prevented
greasing, Painting, and coating with plastic
How does aluminium prevent corrosion
Layer of aluminium oxide to protect metal from further corrosion
What is sacrificial coating
coatings that are more reactive than the metal is so it is corroded rather than the metal its protecting
What is an example of sacrificial coating
zinc is used to galvanise iron
Define electroplating
involves using electrolysis to put a thin layer of a metal on the object:
- the cathode is the iron or steel object
- the anode is the plating metal
- the electrolyte contains ions of the plating metal
How does electroplating prevent corrosion
it improves corrosion resistance
