Topic 5a- Transition metals, alloys and corrosion (paper 1)
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What are the melting points of transition metals?
All high except for mercury which is a liquid at room temperature.
What are the densities of transition metals
They all have high densities.
What are the typical properties of transition metals?
• high melting points • high densities • tendency to form coloured compounds • good catalysts
What is brass an alloy of?
Copper and zinc
What is bronze an alloy of?
Copper and tin
What is a key point to note about gold in jewellery?
Not pure gold as it is too soft. Often alloys including zinc, copper and silver.
What does 24 carat mean?
100% gold
What would 18 carat mean?
75% gold
What is magnalium made from?
Magnesium and aluminium
What is the equation for corrosion
metal + oxygen + water → hydrated-metal-oxide
What is corrosion?
The oxidation of metals.
What are the two methods that can be used to prevent corrosion?
• creating a barrier • sacrificial method • exclusion of water • exclusion of oxygen
What is electroplating?
Using electrolysis to coat the surface of one metal with another metal.
What is sacrificial protection?
Placing a more reactive metal witht the other metal to stop elements reacting with the less reactive one.
What are uses of brass?
• Has low friction so is often used in water taps or door fittings
What are uses of bronze?
• statues • medals
What are uses of aluminium alloys?
• light, so useful in aircraft manufacture
What is magnalium (higher and lower contents) used for?
• (lower) aeroplane parts as it is light and strong • (higher) fireworks because its bright like magnesium, but also a bit more stable