Metals Flashcards
What happens in a displacement reaction
The more reactive metal displaces the other and ends up in solution
What is a spectator ion
An ion that is in the reaction but doesn’t take part
How do you write the ionic equation
Split all compounds into its ions
& Cross out the spectator ions
How can you measure reactivity with different solutions in a reaction
See which has the most vigorous reaction
What is the life cycle assessment
Assesses wether something is ‘worth’ recycling
Name 3 advantages of recycling
Conserves natural reserves of metal ores so need to mine is reduced
Less waste metal ends up in landfill sites
Less pollution produced
Name 3 disadvantages of recycling
Difficult to sort materials
Cost and energy used in collection is high
Sometimes it can be more expensive to recycle than to extract new metals
List the steps in the life cycle of a metal
Metal ore is extracted
Pure metal is extracted from its ore by electrolysis
Metal is shaped and processed into product
Product is sold and used by consumer
Product is thrown into landfill or recycled
How can you tell if it is better to recycle or to extract new metal
If more energy is required to extract the new metal then it is better to recycle
What is an ore
A rock containing a metal compound
There needs to be enough of it for extraction to be economically viable
What can reduction also mean other than gain of electrons
Loss of oxygen
What can oxidation also mean other than loss of electrons
Gain of oxygen
What are redox reactions
A reaction in which oxidation AND reduction take place
Eg. Electrolysis
Is a metal being isolated from their ore reduction or oxidation
ALWAYS reduction
Metals more reactive than WHICH ELEMENT can be extracted using ELECTROLYSIS
Carbon
What are the 2 ways small amounts of copper can be extracted from their ores
Bioleaching and phytoextraction
What is bioleaching
Bioleaching uses bacteria grown on a low grade ore
The bacteria produce a solution containing copper ions called a leachate
Copper is extracted from the leachate by displacement and purified by electrolysis
Are the melting points of transition metals typically high or low
High
Do transition metals typically have high or low densities
High
Name 4 properties of transition metals
Ductile
Shiny
Malleable
Conducts electricity
Do transition metals typically form coloured compounds
Yes
What is an alloy
A mixture of a metal with at least one other element
What does adding other elements to a metal do
It changes the overall structure and so changes its properties
What can scientists do by changing the amount of each element in an alloy
Material scientists can custom make alloys to fit a given job
What is the alloy brass used for and why
Door knobs, buttons and musical instruments BECAUSE it does not tarnish
What is the alloy amalgam used for and why
Dental fillings BECAUSE it can be shaped when warm and resists corrosion
Why is yellow gold a different colour from pure gold
Because it is an alloy of copper and silver
Adding more copper gives redder shades
Why is steel stronger than iron
In pure iron the atoms are arranged in dense layers (these layers can slide over each other which means iron is quite soft)
The atoms of other elements are different sizes so when they are added to iron they distort the regular structure
This makes it harder for the layers to slide past each other and so increases strength
What happens when metals react with oxygen in air
They oxidise to form metal oxides
What is tarnishing
Metals may form a thin layer of tarnish when they oxidise
This layer stops oxygen reaching the metal preventing any further oxidation
Eg. Statue of Liberty
What is corrosion
Corrosion happens when the metal continues to oxidise and so overtime becomes weaker
What is rusting
Corrosion of iron or steel when reacting with oxygen and water
How can rusting be prevented by keeping air away
metal kept in unreactive atmosphere of nitrogen or argon
How can rusting be prevented by keeping water away
Use a desiccant powder that absorbs water vapour
What are the physical barriers used to prevent rusting
Painting, coating with plastic, greasing and oiling
What is sacrificial protection
A method of rust prevention that does not rely on keeping water and oxygen away
How is a sacrificial metal chosen
Any metal that oxidises more easily than the metal that is at risk from rusting
Explain how magnesium prevents steel from rusting
Magnesium is more reactive than steel
Magnesium acts as the sacrificial protection as it oxidises faster than steel
Mg —-> Mg2+ + 2e-
Magnesium has been oxidised because it has lost electrons
