10. Metals Flashcards
Where in the reactivity series is carbon and hydrogen
Carbon- between aluminium and zinc
Hydrogen - between lead and copper
Pattern of reactivity series
Only metals above H will react with water or steam and with HCl
Above H -> displace H from its acid and hydrogen cannot reduce their oxide
Above C -> their oxide cannot be reduce by carbon
An element can displace another from its oxide if it is more reactive
A more reactive metal will displace a less reactive metal from a solution of its salt
More reactive -> more easily to loses its valency electrins
When is it easier to lose electron from the outer shell
More electron shells between the nucleus and the valency electron -> valency electron are further away from the pull of nucleus
Fewer protons in the nucleus (less nucleus charge) to pull electrons toward them
What is thermal decomposition
When we heat a substance and it break down to form two or more different product
Thermal decomposition of metal hydroxide
Metal oxide + water
Alkali metal hydroxides do not decompose except Lithium
Happen faster the further down the series
Thermal decomposition of nitrates for alkali metal
Except lithium
Metal nitrite + oxygen
Thermal decomposition of other metal and lithium
Metal oxide + nitrogen dioxide + oxygen
Nitrates of very unreactive metal (silver) decompose to form metal, nitrogen dioxide and oxygen
Why aluminium seems unractive
When the surface of freshly made Al is left in the air, a thin layer of Al oxide quickly forms on its surface
The layer is not very thick but it is enough to make the metal resistant to corrosion
The tough oxide layer sticks to the surface of Al very strongly and doesn’t flake off
Oxide layer is unreactive
Reactivity series
Potassium Sodium Calcium Magnesium Aluminium Zinc Iron Lead Copper Silver Gold
Uses of aluminium
In the manufacture of aircraft because of its strength and low density
In food containers bc it is resistant to corrosion - unreactive oxide layers on its surface
Steel alloy
Made up of iron and other element
Mild steel
96% iron, 4% carbon
Soft, malleable, can be drawn into wires easily
Use for car bodies and machinery
Stainless steel
70% iron, 20% chronium, 10% nickel
Strong, resist corrosion
Use in chemical plants and cutlery
Uses of zinc
Zinc is used to galvanise to prevent rusting
To galvanise a steel object, we dip object into liquid zinc
The zinc forms a coating on the surface of the steel
Used for roofing - weather resistant
Zinc is used for making brass (70% zinc, 30% copper)
Use of copper
Electrical wiring - high electrical conductivity
Cooking utensil - good conductor of heat
