Metals Flashcards
Metallic bonding
electrostatic attraction between the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electron
Describe and explain 2 characteristics of metallic bonding
1) good electrical conductivity
There are free electrons available to move through the structure and carry charge
2) malleability and ductility
Layers of positive ions can slide over one another
general physical properties of metals
1) thermal and electrical conductivity
2) malleability and ductility 3) melting points and boiling points (R)
general chemical properties of metal
1) Metals that react with cold water
metal + water → metal hydroxide + hydrogen
2) When acids and metals react, the hydrogen atom in the acid is replaced by the metal atom to produce a salt and hydrogen gas, for example iron:
metal + acid → salt + hydrogen
3) When metals react with oxygen a metal oxide is formed
metal + oxygen → metal oxide
Transition elements properties [4]
1) have high densities 2)have high melting points 3) form coloured compounds
4) often act as catalysts as elements and in compounds (M)
Explain the apparent unreactivity of aluminium in terms of its oxide layer [3]
1) Aluminium is high in the reactivity series, but in reality, it does not react with water and the reaction with dilute acids can be quite slow
2) This is because it reacts readily with oxygen, forming a protective layer of aluminium oxide which is very thin
3) This layer prevents reaction with water and dilute acids, so aluminium can behave as if it is unreactive
Uses of aluminium and why
1) aluminium in the manufacture of aircraft because of its low density
2) aluminium in the manufacture of overhead electrical cables because of its low density and good electrical conductivit
3) aluminium in food containers because of its resistance to corrosion
Uses of copper and why
copper in electrical wiring because of its good electrical conductivity and ductility (R)
Define alloy
a mixture of a metal with other elements
Brass is a mixture of
brass as a mixture of copper and zinc
Stainless steel is a mixture of [4]
Iron, chromium, nickel and carbon
why are alloys prefered?
alloys can be harder and stronger than the pure metals and are more useful
alloys in terms of their physical properties
1) different sized atoms which is hard for layers to slide over each other
2) Prevents rusting by combining several metals or elements that form a protective layer on top of the metal surface.
why are alloys prefered? explained
alloys can be harder and stronger than the pure metals because the different sized atoms in alloys mean the layers can no longer slide over each other
State the conditions required for the rusting of iron and steel to form hydrated iron(III) oxide (M)
water and air (actually oxygen in the air)
