Metals Flashcards
What are the two components in the structure of a metal?
A lattice of positive metal ions and a ‘sea’ of delocalised electrons.
Define metallic bonding:
Metallic bonding is the electrostatic attraction between the positive metal ions and the negative delocalised electrons.
Is metallic bonding a usually strong or weak attraction?
Usually a very strong reaction.
What are the 3 properties of metals?
-High melting points
-Conduct electricity
-Malleable
Why do metals have high boiling points?
Because the metallic bonding is usually very strong, so lots of energy is needed to break it.
Why do metals conducts electricity?
Because the delocalised electrons are free to move through the lattice.
Why are metals malleable?
Because the layers of metal ions can slide over each other.
What is thermal decomposition?
When heat energy is used to break down a substance.
What do metal carbonates decompose into?
Metal Carbonate ->
Metal Carbonate -> Metal Oxide + Carbon Dioxide
What does the thermal decomposition of copper carbonate look like?
Copper carbonate (green solid) -> Copper Oxide (black solid) + Carbon Dioxide (colourless gas)
Carbon dioxide is often collected by downward delivery, what does this mean?
As carbon dioxide is denser than air, it sinks to the bottom of a tube and can stay there until you want to use it.
Metal + Water ->
Metal + Water -> Metal Hydroxide + Hydrogen
What are the two observations (in the metal + water reaction) between magnesium and water?
-Effervescence as hydrogen is produced
-Solid disappears due to being used up in the reaction
What is another name for the metals in group 1 of the periodic table?
Alkali metals.
What is one word to describe the reaction between group 1 metals and water?
Violent.
What are the four similar observations in the reactions between Li, K and Na with water?
-Solid floats
-Effervescence
-Solid Moves
-Solid disappears
Why does the solid float in a group 1 metal + water reaction?
It is less dense than water.
Why does the solid move in a group 1 metal + water reaction?
The effervescence propels it around the surface of the water.
Why does the solid disappear in a group 1 metal + water reaction?
It is used up in the reaction.
What colour does a universal indicator turn in water after a group 1 metal and water reaction?
Why?
Dark blue because the metal hydroxides are alkalis because they donate OH-.
What is the reaction between Li and water like?
Fast.
What is the reaction between Na and water like?
Faster than lithium and Na melts
What is the reaction between K and water like?
The fastest, K melts and there is a lilac flame.
What is the group 1 metal reactivity trend?
The group 1 metals get more reactive as you go down the group.
What do group 1 metals have to do to their electrons when they react?
They have to lose 1 electron to get an outer shell
Why do group 1 metals become more reactive as you go down the group?
It’s easier for them to lose an electron when you go down because:
- The atoms get bigger and have more shells
- the outer-electron is further from the nucleus
- The attraction between the nucleus and outer-electron is weaker
- Less energy is needed to break the attraction
Metal + Steam -> ?
Metal + Steam -> Metal oxide + Hydrogen
Describe the reaction between magnesium and steam:
-Usually conducted in a horizontal tube
-Wet wool is heated at the end of the tube to generate steam for the Mg to react with
-The H2 gas is ignited to safely destroy it
Why do metals react with cold water and hot steam to produce different products?
Steam has more energy, so both bonds in the water molecule can break.
Acid + Metal ->
Acid + Metal -> Salt + Hydrogen
A salt is a compound formed when…
A salt is a compound formed when H is displaced from an acid.
What are the 2 important observations in an acid + metal reaction?
-The metal disappears because it is used up in the reaction
-There is fizzing because hydrogen is produced
What elements are not possible to react with an acid and why?
-Au, Ag and Cu
-Because they are less reactive than H, so cannot replace it.
What elements are not allowed to react with an acid and why?
-Li, Na and K
-Because their reaction with acids is too violent
What is a metal displacement reaction?
More reactive metals can displace less reactive metals from their compounds.
Give an example of a metal displacement reaction:
Magnesium can displace copper from copper sulphate
Mg(s) + CuSO4(aq) ->
grey solid blue solution
Cu(s) + MgSO4(aq)
Pink- colourless solution
orange solid
What are 2 observations in a metal displacement reaction?
-Solid colour change
-Solution colour change
Where are most metals found and as what?
In the earth’s crust as compounds with oxygen and sulphur.
Why are most metals found as compounds with oxygen and sulphur?
Because over a long time those metals have reacted with oxygen and sulphur.
What are the rocks containing specific metal compounds called?
Ores.
What metals aren’t found with oxygen and sulphur and why?
Gold (Au) and silver (Ag) as they are too un-reactive to have combines with sulphur or oxygen.
How are gold and silver found naturally?
They are found ‘native’, which means chemically uncombined
What process separates metals from their compound?
Chemical extraction.
What 2 ways are metals chemically extracted from their compounds?
- Using electricity
- Carbon extraction
When is electricity used to extract metals from their compounds?
When the metal is more reactive than carbon so cannot be displaced by carbon.
When is carbon used to extract metals from their compounds?
When metals are less reactive than carbon so can be displaced by carbon.
Define a redox reaction:
Using carbon to displace a metal from its oxide is a redox reaction.
Define reduction in terms of oxygen:
Loss of oxygen
Define reducing agent in terms of oxygen:
What takes oxygen away from something else
Define oxidation in terms of oxygen:
Gain of oxygen
Define oxidising agent in terms of oxygen:
Gives oxygen to something else
Define redox in terms of oxygen:
Reduction and oxidation in the same reaction
What is rusting?
Rusting is a chemical process by which iron is oxidized to form rust.
What is the chemical name for rust:
Hydrated iron (III) oxide
Rusting requires what 2 substances?
Oxygen and water.
What 3 methods prevent rusting?
- Using barriers
- Sacrificial protection
- Galvanising
List 3 barriers that can be used to prevent rusting:
Paint, plastic or oil.
What happens as soon as the barrier on iron breaks?
Rusting happens
How do you choose the coating material when using barriers to prevent rusting?
It depends on the use of the iron. For example oil/grease for moving parts (eg bike chains), paint/plastic for larger, stationary objects (eg buckets)
What is sacrificial protection and how does it work?
Attaching a block of more reactive metal (eg magnesium) to the iron. This works by displacing the iron from rust as soon as the rust forms.
What is the disadvantage of sacrificial protection?
The block of magnesium has to be replaced often.
What is galvanising?
Coating the iron in zinc.
How does galvanising work in 2 different ways?
-Coating prevents oxygen and water coming into contact with the iron
-Even if the coating cracks, zinc is more reactive than iron so acts as sacrificial protection too
What are alloys?
Alloys are mixtures of metal with one or more other elements, usually other metals or carbon.
What are 3 commonly known alloys:
-Steel
-Brass
-Bronze
What is steel made up of?
Iron + carbon
What is brass made up of?
Copper + zinc
What is bronze made up of?
Copper + tin
Are alloys harder or softer than pure metals? Why?
They are harder than pure metals because the different sized atoms/ions prevent the layers of metal ions from sliding over eachother.
Are allows more or less malleable than pure metals?
Less malleable.
What do the different types of steel depend on?
The amount of carbon.
What is the use of iron and why?
Used to make steel because steel is more useful than iron.
What is the use of low-carbon steel and why?
How much carbon is in this?
Used to make ships, cars, bridges etc because its strong, but low-carbon so can be hammered into various shapes.
0.1%C
What is the use of high-carbon steel and why?
How much carbon is in this?
Used to make tools like knives and screwdrivers because it’s high carbon so less malleable and stiffer than low-carbon.
1%C
What elements is stainless steel made up of?
Iron, carbon and chromium
1% C 10% Cr
What is the use of stainless steel and why?
Used for cutlery, cooking utensils and kitchen sinks because the Cr forms an oxide layer that resists corrosion, so stays shiny and clean.
What is the use of copper and why?
Used for wires, cooking pans and water pipes because it’s an excellent conductor of electricity, an excellent conductor of heat, un-reactive and malleable
What is the use of aluminium and why?
Used for aircraft bodies and power cables because it’s low-density, high strength and conducts.
