Please enable JavaScript.
Coggle requires JavaScript to display documents.
Topic 4a - Transition metals alloys and corrosion - Coggle Diagram
Topic 4a - Transition metals alloys and corrosion
Alloys
Pure metals are malleable as all the metal ions are the same size and in a regular arrangement, allowing layers to slide over eachother
In alloys different sized atoms disrupt the layers
This makes it harder for the layers to slide over eachother
This makes an alloy stronger
Common alloys
Copper alloys
Brass - copper and zinc
Used in water taps and door fittings
Bronze - copper and tin
Statues and decorative objects
Gold alloys
Jewellery
Zinc, copper and silver are used to harden gold
Aluminium
Low density
Magnalium - aluminium and magnesium
Magnalium is stronger, lighter and corrodes less easily
Used in aeroplanes
Steel
Pure iron is too soft for most purposes so is mixed with carbon and other metals to produce steel
Stainless steel is an iron alloy that resists corrosion
Corrosion
Metals corrode in the presence of air and water
Oxidation of metals causes corrosion
Nail practical
Nail + boiled water and oil- no rust
Nail with water and air - rust
Nail + CaCl2 and air - no rust
Preventing corrosion
Electroplating
Uses electrolysis to coat the surface of one metal with another
The cathode is the object that is going to be electroplated
The anode is the metall that will end of coating the surface of the object
The electrolye is a solution containing the metal ions of the metal that is being plated on to the object
Uses
Stop corrosion
Decoration
Acts as a barrier in order to exclude oxygen and water
Sacrificial protection
Placing a more reactive metal with iron
Water and oxygen will react with the sacrifical metal instead of the iron
Galvanising, a coat of zinc is put onto an iron object
Corrosion - destruction of materis by chemical reactions with substances in the environment
Transition metals
Properties
High metling point - electrostatic forces of attraction between positively charged metal ions and sea of electrons
High density
Form coloured compounds
Used as catalysts (like iron in the Haber process)
Most metals are transition metals