5) Separate Chemistry
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Where are transition metals found?
In the middle of the periodic table
How does transition metal melting point compare to alkali metals?
Higher melting point
How does transition metal strength compare to alkali metals?
Stronger and harder
How does transition metal density compare to alkali metals?
Higher density More mass for the same volume
How does transition metal reactivity compare to alkali metals?
Less reactive
What are special properties of transition metals?
Can form ions with diofferent positive charges Can form different coloured compounds Often used as catalysts
What transition metals are used at catalytic converters in cars?
Platinum Rhodium
What is corrosion?
The gradual destruction of metals because of reactons with oxygen and water
What is the reaction of rusting?
Iron + oxygen + water –> hydrated iron (III) oxide
What is the rusting experiment?
Place iron nail in boiling tube under conditions: Only water - no rust Only air - no rust Air and water - rust
What are the 3 main ways of preventing corrosion?
Coatings Galvanising Sacrificial method
What is galvanising?
A hybrid of coatings and sacrifical method Protected metal is sprayed with more reactive metal (coating) If more reactive metal is damaged it protects as sacrifical metal
What are corrosion coatings?
Applying a barrier such as greasing, painting or electroplating
What is a disadvantge of coatings?
Any damage leads to metal becoming exposed
What is the sacrifical method of corrosion?
Metal requiring protection has more reactive metal atatched to it Water and oxygen will stop reacting with protected metal
What process is used to electroplate objects?
Electrolysis
What is the process of electroplating?
Metal to be electroplated placed at cathode and coating metal at anode
Why do we electroplate?
To coat a cheaper metal with a more expensive one (jewellery)
What are alloys?
A combination of 2+ elements with at least 1 metal
Why are alloys stronger than pure metals?
Ions of different sizes cannot slide across each other easily
What are uses of aluminium alloys?
Armour plating Manufacturing planes
What is bronze an alloy of?
Copper Tin
What is bronze used for?
Making coins Electrical hardware Statues
How many carats is pure gold?
24 carats