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7/29/2019 metals and their properties.pdf
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Metals and their Properties
Metals have distinctive properties such as: 1. Electrical Conductivity
2. Good Thermal Conductivity 3. Strength
4. Malleability.
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Reaction of MetalsReaction of Metals With Oxygen:
All metals react with Oxygen. The morereactive the metal the quicker the reaction.
In the Lab the Oxygen is produced by heatingPotassium(v)Manganate.
The Brighter the glow the more the reactive the
metal. Less reactive metals produce a duller glow General Equation:
Metal + Oxygen Metal Oxide
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Metals + Oxygen (contd)
Potassium (v)Manganate
acts as a source ofOxygen when Heated
Mg metal is
placed
between two
pieces of
ceramic wool
The more active the metal the brighter
the glow
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Reactions of MetalsReactions of Metals With Water:
Only Metals above Hydrogen in the ActivitySeries react with water.
In fact only the first three react withCold water.
The remaining metals above Hydrogen must be
treated withSteam before a reaction will take place.
General Equation:
Metal + H2O Metal Hydroxide + H2
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Reactions of MetalsReactions of Metals
With Acids:Only Metals above Hydrogen in the
Activity Series react with Acids.
General Equation:
Metal + Acid Salt + Hydrogen
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Metals and Acid(contd).
PopPop
When a metal is reacted with
an Acid it produces H2 gas
which burns with a POP!
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Alloys An Alloy is a mixture of metals or metals and
other elements. Alloys are made to change the properties of the
metal e.g.to make them harder, more pleasing
on the eye or to make them more resistant to
Corrosion.
Examples are: Brass(a mixture of Cu&Zn), Gold(Au&Cu.The greater the proportion of Cu the
lower the no.of carats),Stainless Steel(Fe,Ni&Cr)
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Metal Ores
Most metals are found combined to other elementssuch as, Oxygen and Sulphur in the earths
crust.These are calledMetal Ores.
Only Gold, Silver and Platinum are found
uncombined.
As a result metals must be mined and then separatedfrom their Ores by Metal Extraction
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Extraction of Metals from their
Ores
Metals low down in the Electrochemical Seriesform weak bonds with other elements. As a
result Ores of these metals can broken up easily
to obtain the metal.
Ores of metals high up in the Electrochemical
series contain stronger bonds and thereforerequire more sophisticated and expensive
methods of Extraction
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Electrochemical Series
PotassiumSodium
CalciumMagnesium
Aluminium
Zinc
IronNickel
Tin
Lead
HYDROGEN
Copper
Mercury
StealingGold
Plates
Can be Broken by Heat alone
Separated from ore by Heating with
CHARCOAL, thus releasing CARBON
DIOXIDE.
Must be Electrolysed to release
Metal from Ore