Metals Flashcards
(19 cards)
Properties of transition metals
High melting point
High density
Form cloloured compounds
Used as catalyst
What causes metals to corrode
Oxygen reacts with metal to form metal oxide
Why is corrosion of a metal a redox reaction
The metal losses electrons so is oxidised
Oxygen gains electrons so it’s reduced
What is rusting
Corrosion of iron when it reacts to oxygen and water in the air
Sacrificial protection
Protection from rusting by galvanising- with a more reactive metal
Outer metal corroded first and prevents corrosion of inner metal
How to stop iron rusting
Paint the metal
Coat metal in oil
Cover in plastic
What metal is used in galvanising iron
Zinc
What is electroplating
A process in which a metal is coated with a layer of another metal
Reasons for electroplating
To make a metal more resistant to corrosion
To improve the appearance off a metal
How electroplating works
Similar setup to electrolysis
Metal being coated is the cathode
The metal that forms the layer - anode
Why are pure metals malleable
The atoms lie in uniform rows which able to slide over on another
What is an alloy
A mixture of two or more metals or a metal and another element
How do alloys increase strength
Alloys contain metals with different sized atoms
This prevents layers and atoms sliding over one another easily
Why is iron alloyed with other metals to produce steel
Iron is brittle
Low carbon steel: Malleabke so hard for sheeting
High carbon steel: Hard so used for cutting tools
Stainless steel: corrosion resistant so used for cutlery
Why is copper used in electrical cables
Very good electrical conductor
Aluminium used in aircraft’s
Low density
Why is gold used in jewellery
Very unreactive
Appearance won’t be affected over time
What is magnealium and its uses
Alloy of magnesium and aluminium
Lighter and stronger than aluminium
More resistant to corrosion
Used for car and aircraft
What is brass and its uses
Alloy of copper and zinc
Hard and resistant to corrosion
Used for decorative hardware like plumbing fittings
