P1C13 - Transitions bet metals, alloys, corrosion Flashcards
Where are the transition metals found?
In the middle of the periodic table.
(To their left is g2 and to their right is g3)
What are the properties of the transition metals?
- Great strength + hardness
- High density
- Low reactivity
- High melting points
Why are transition metals useful for chemists?
- Can form ions with different positive charges
- Can form different coloured compounds
- Often used as catalysts
What 2 metals are typically used as catalytic converters in cars?
Platinum
and rhodium
Whats the catalyst used in the Haber process?
Iron
What is corrosion?
The gradual destruction of metals because of chemical reactions between metals and the oxygen and water around them.
What is the rusting reaction?
Iron + oxygen + water → hydrated iron(III) oxide.
What is the rusting experiment?
Take a boiling tube and put an iron nail inside under three different sets of conditions and see if it rusts:
Only water - no rust.
Only air - no rust.
Air and water - rust.
What are the 3 methods to prevent corrosion/rusting?
Coating
Sacrificial method
Galvanising
What are examples of coating?
Greasing, painting, electroplating
What is the sacrificial method to prevent rusting?
The attachment of a more reactive metal to the metal that needs protecting.
What is galvanising?
Combination of coating and the sacrificial method.
How does electroplating work?
The process works by placing the metal to be electroplated at the negative electrode (cathode) and the coating metal at the positive electrode (anode).
What is an alloy?
An alloy is a combination of 2+ elements, where at least 1 is a metal.
Why are the ions in an alloy different sizes?
To make it harder for the layers to slide across each other when a force is applied to the alloy.
This means that allows are stronger than pure metals.
