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Metals (Chemistry- Part 1), Apparatus to investigate how metals like Mg…
Metals
(Chemistry- Part 1)
Introduction:
Common properties:
strong, malleable, ductile, sonorous, shiny when polished, good conductors of heat and electricity, have high melting and boiling points, high densities.
Metals lie on the
left hand side
of the metalloid line.
Over 80% of the elements are metals.
They
have high melting and boiling points
due to
strong metallic bonds
. Large amounts of energy is needed to overcome these forces.
Good conductors of electricity:
This is because they have
delocalised electrons
(electrons can flow and conduction of electricity occurs).
Malleability and ductility:**
Layers of positive ions can easily slide over each other. ** Are flexible and can maintain electrostatic forces. Can be hammered into different shapes.
Chemical properties of metals:
They reaction with oxygen to form oxides.
Metal oxides are
basic
. They neutralise acids to form salts and water.
Unreactive metals do not react with oxygen, while reactive ones do. Some react very slowly.
Metal + oxygen ---> Metal oxide
Form positive ions
when they react.
Charge on the ion is the same as the group number. Transition elements have variable valency.
Reactivity with water:
Metals react with
cold water, warm water or steam
.
Reactive metals react with cold water form hydroxide and hydrogen gas.
E.g. Ca + H2O ---> Ca(OH)2 + H2
Unreactive metals react with water to form metal oxide and hydrogen gas.
E.g. Zn + H2O (g) ---> ZnO + H2
Reactivity with acids:
Most metals (reactive) react with dilute acids such as HCl.
Metal + Acid ---> Salt + Hydrogen gas
Properties and uses:
All metals have
specific properties
. E.g.
Iron
- is
strong
and
malleable
- used to make
gates
Gold
-
unreactive
,
malleable
and
shiny
-
jewellery
Aluminium:
Aeroplane bodies: Low density
Power cables: Good conductor of electricity
Saucepans: Good conductor of heat
Food cans: non- toxic, resistant to corrosion
Window frames: resistant to corrosion
Copper:
Electrical wires: Good conductor of electricity and ductile
Water pipes: Non- toxic, unreactive, easy to work with and bend
Zinc:
Protecting steel from rusting: Sacrificial protection
Coating and galvanising: resistant to corrosion
Torch batteries: Gives a current
Alloys:
An alloy is a mixture of 2 or more elements.
Turning a metal into an alloy
changes its properties and makes it more useful.
E.g.
Zinc + Copper ---> Brass (unreactive, hard, strong, shiny)
E.g.
Steels: Mind steel, High carbon steel, Low alloy steel, stainless steel.
Why do alloys have different properties?
Alloys distort regular elemental arrangements.
This distorted structure means that the layers cannot slide over each other which makes it stronger/ harder.
Some alloys even become resistant to corrosion.
Apparatus to investigate how metals like Mg react with water* (refer notes)
Uses of metals: