5.1-5.7 Transition Metals, Alloys and corrosion Flashcards
What type of metal are most metals?
Transition metals
Give three properties of a transition metal
.High melting point .High density .Form coloured compounds .Have ions with many different charges .Are useful as catalysts
What does the oxidation of metals lead to?
Corrosion
Give three ways rusting of Iron can be prevented
.Exclusion of Oxygen
.Exclusion of Water
.Sacrificial protecting
How can the rusting of iron be prevented by the exclusion of oxygen?
.Painting
.Coating with plastic
.Using oil or grease
.Oxygen can be kept away by storing the metal in a vacuum container
How can the rusting of Iron be slowed down/stopped with the exclusion of water?
.Painting
.Coating with plastic
.Using oil or grease
.Use a desiccant in the container (Absorbs water vapour)
What is Sacrificial protection?
.Where the metal you must protect from rusting is galvanised with a more reactive metal
.This metal will rust first and prevent water and oxygen reaching the layer underneath
What is electroplating?
.It is the process where the surface of a metal is coated with a layer of a different metal
How can electroplating improve the resistance of a metal?
.It acts as a barrier which excludes oxygen and water
How can electroplating improve appearance?
.You can electroplate a metal with a more attractive metal like gold which will not corrode and is more attractive
How is electroplating carried out?
The metal to be plated is at the cathode and the metal you are plating it with is at the anode
.Have a solution containing ions of the metal being used to do the plating
Why does converting metals into alloys often increase the strength of a metal?
.All the metal ions are the same size and can slide over each other in regular arrangement relatively easily
.In an alloy you have different metals with different sized ions
.This disrupts the structure and prevents the ions from being able to move as easily
.This leaves a much harder, stronger metal
What two metals is steel a mixture of?
Carbon and Iron
Give two specific uses alloys can be designed for
.Low carbon steels can be easily shaped-used for sheeting
.High carbon steels are hard-used for cutting tools
What is the density of Aluminium?
Low density
