3.5 Metals Flashcards
Metallic structure
- A lattice of positive metals ions
- A ‘sea’ of delocalised electrons
Metallic bonding
The electrostatic attraction between positive metals ions and (negative) delocalised electrons.
Metallic bonding, strong
The strong electrostatic attraction between positive metals ions and (negative) delocalised electrons requires lots of energy to overcome
Properties of metals
- High melting point
- Malleable
- Conducts electricity
High melting point explanation
Strong electrostatic attraction between positive metals ions and (negative) delocalised electrons requires lots of energy to overcome
Conducts electricity explanation
The delocalised electrons are free to move and can carry charge through the lattice
Malleable explination
The layers of positive metal ions can slide over each other and the delocalised electrons keep the attraction
Thermal decomposition
When heat energy is used to break down a substance
Metal carbonate thermal decomposition
Metal carbonate —> Metal Oxide + Carbon Dioxide
Thermal decomposition of copper carbonate
Copper Carbonate —> Copper Oxide + Carbon Dioxide
Thermal decomposition of copper carbonate: Colour change
Green —> black solid (+ colourless gas)
Downward delivery
Carbon dioxide is denser than air meaning it is collected by downward delivery. It sinks to the bottom until you want to use it.
Metal + Water reaction
Metal + Water —> Metal Hydroxide + Hydrogen
Metal + Water Reaction: Magnesium
Magnesium + Water —> Magnesium Hydroxide + Water
Metal + Water Reaction: Observations
- Solid disappears as it is used up
- Fizzing as gas is given off (hydrogen)
- Metals that are less reactive react slower
What are the group one metals called?
The alkali metals
What do group 1 metals do?
They react violently with water to form metal hydroxides and hydrogen
Observations of Reaction of Lithium, Sodium and Potassium in water
- Fizzing (hydrogen gas)
- Solid floats
- Solid moves
- Solid disappears
What happens to the reactivity as you go down group 1?
The reactivity increases
What are all metal hydroxides?
Alkalis as they have donated OH-
What colour is the universal indicator after reaction of a group 1 metal with water?
Turns dark blue as they are alkali
Observations of potassium reaction with water?
Lilac Flame and melts fastest
Trend going down group 1
As you go down group one, there are more shells on each atom meaning it is easier to lose the outer electron as it’s further away from the nucleus. Therefore less energy is needed to break the attraction.
What happens if you react a metal with steam
Doesn’t produce a metal hydroxide, only a metal oxide. This is because steam has more energy so both bonds in the water molecule can break.
How are most metals found?
In the earths crust as compound with oxygen and sulphur, these are called ores
Why are gold and silver metals special?
They are too unreactive to combine with oxygen and sulphur, they are found ‘native’ which means chemically uncombined
Metal more reactive than carbon
If a metal is more reactive than carbon it has to be extracted using electrolysis
Electrolysis
In water, molecules that are positive go to one side, and negative to another, separating them
Carbon Extraction
-Heat with carbon and the metal is displaced by the carbon, this only works because it is more reactive than carbon.
Carbon Extraction Example
Carbon + Copper Oxide —> Carbon Dioxide + Copper
Redox reaction
Reduction
Loss of oxygen, Gain of electron
Reducing Agent
Takes oxygen away from something else
Oxidation
Gain of oxygen, Loss of electrons
Oxidising Agent
Gives oxygen to something else
Redox
When both oxidation and reduction occurs
Rusting
When iron is oxidised to form rust
Rusting requires two substances
Water and Oxygen
Barrier method
Coat iron in paint, oil, grease or plastic so the water and oxygen can’t get into the iron
But, the coat will wear away meaning it has to be replaced
Sacrificial Protection
Attach a more reactive metal so it will displace the iron
But, you need to replace the more reactive metal often (usually magnesium)
Galvanising Method
Barrier method & Sacrificial protection combined, you coat the iron in zinc, it’s more reactive and water and oxygen can’t get in.
But it is expensive and needs to be replaced.
Alloy
Mixtures of a metal with one or more other elements (usually other metals or carbon)
Alloy characteristics
Harder than pure metals because different sized atoms prevent the layers from sliding over each other (less malleable)
Use of iron
Making steel as it’s more useful
Low-Carbon steel use
Ships, Cars, Bridges, it’s strong but still can be hammered into shape
High-Carbon steel use
Tools, less malleable and stiffer than low carbon steel
Stainless steel use
Cooking pans, cutlery, kitchen sinks, (Cr forms oxide layer that resists corrosion meaning it’s shiny)
Copper use
Wires, Water pipes (Conductor or heat and electricity, malleable)
Aluminium use
Aircraft bodies, power cables (low density, high strength, conductors)
