© Oxford University Press 2009 7.1 Using Metals Metals in the periodic table Most elements are...
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Transcript of © Oxford University Press 2009 7.1 Using Metals Metals in the periodic table Most elements are...
© Oxford University Press 2009
7.1 Using Metals
Metals in the periodic table
Most elements are metals
The elements on the left of the stepped line are metals.
© Oxford University Press 2009
7.1 Using Metals
Find 3 essential properties of metals for water pipes
• Malleable
• Do not react with water or air
• Strong
More information:
Lead is no longer used for water pipes because it can make poisonous solutions.
Metal choices…
…copper or lead
© Oxford University Press 2009
7.1 Using Metals
Find 4 essential properties of metals for saucepans
• Good conductors of heat
• Do not react with water
• Malleable
• Strong
Metal choices…
…copper, aluminium or stainless steel
© Oxford University Press 2009
7.1 Using Metals
Find 4 essential properties of metals for jewellery
• Shiny
• Hard
• Malleable
• Do not react with water or air
Metal choices…
…gold, silver, platinum
© Oxford University Press 2009
7.1 Using Metals
Find 3 essential properties of metals for electrical wiring
• Ductile
• Good conductor of electricity
• Do not react with water or air
More information:
Copper is a better conductor than aluminium
Metal choices…
…copper, aluminium
© Oxford University Press 2009
7.1 Using Metals
Find 4 essential properties of metals for long-distance power cables
• Ductile
• Good conductors of electricity
• Low density
• Do not react with water or air
More information:
Copper is 3 times denser than aluminium
Metal choices…
…copper, aluminium
© Oxford University Press 2009
7.1 Using Metals
Find 4 essential properties of metals for aeroplanes
• Low density
• Malleable
• Do not react with water or air
• Strong
More information:
Aluminium does not react with water or air because it forms a protective coating on its surface
Metal choice…
…aluminium
© Oxford University Press 2009
7.1 Using Metals
Find 4 essential properties of metals for light bulb filaments
• Ductile
• Glow when hot
• Very high melting points (so they don’t melt when they glow)
• Good conductor of electricity
More information:
Tungsten has the highest melting point of all metals (3410 ºC)
Metal choice…
…tungsten
© Oxford University Press 2009
7.1 Using Metals
Find 2 essential properties of metals for a tip-over switch
Tip-over switches in electric heaters switch off the current if the heater falls over, so preventing fires.
• Good conductors of electricity
• Liquid at room temperature
More information:
Mercury is the only metal that is liquid at room temperature. Its melting point is -38.9 ºC and its boiling point is 357 ºC
Metal choice…
…mercury
© Oxford University Press 2009
7.1 Using Metals
Find 8 properties that most metals have
• Strong
• Solid at room temperature (melting point above 25 ºC)
• Good conductor of electricity
• Good conductor of heat
• Shiny (at least when first cut)
• Malleable
• Ductile
• Hard
© Oxford University Press 2009
7.1 Using Metals
But metals are not all the same…
© Oxford University Press 2009
7.1 Using Metals
Extreme metals
Melting points
Highest – tungsten melts at 3410 ºC.
Lowest – mercury melts at -38.9 ºC, so it is liquid at room temperature.
© Oxford University Press 2009
7.1 Using Metals
Extreme metals
Density
Highest – iridium and osmium (22.5 g/cm³)
(lead 11.3 g/cm³)
Lowest – potassium (0.86 g/cm³)
(aluminium 2.70 g/cm³)
So a centimetre cube of iridium weighs 26 times as much as one of potassium!
© Oxford University Press 2009
7.1 Using Metals
Extreme metals
Reactions in water and air
Don’t react at all – platinum and gold
React violently – potassium, rubidium, caesium
© Oxford University Press 2009
7.1 Using Metals
Metal patterns
Different metals have many similarities…
…but many differences
In this unit you will…
• Look at some properties of different metals
• Find patterns in these properties
• Use the patterns to predict metal reactions