C10 - Metals Flashcards
Properties of metals (name 3)
- Conduct heat and electricity
- Are malleable (can be hammered and made into different shapes) and ductile (can be drawn into wires)
- Tend to be lustrous (shiny)
- Have high density and usually have high melting points
- Form positive ions through electron loss
- Form basic oxides
Properties of non-metals (name 3)
- Do not conduct heat and electricity
- Are brittle when solid and easily break up
- Tend to be dull and nonreflective
- Have low density and low melting points (many are gases at room temperature)
- Form negative ions through electron gain (except for hydrogen)
- Form acidic oxides
Metal and water reaction
metal + water → metal hydroxide + hydrogen
Metal and acid reaction
metal + acid → salt + hydrogen
Metal and oxygen reaction
- Unreactive metals do not react with oxygen
- Some reactive metals like alkali easily can
- Copper and iron can also react but slowly
metal + oxygen → metal oxide
Uses of aluminium and their reason (name 3)
- Aeroplane bodies
- high strength-to-weight ratio, low density
- Overhead power cables
- good conductor of electricity, low density
- Saucepand
- good conductor of heat
- Food cans
- non-toxic, resistant to corrosion and acidic food stuffs
- Window frames
Uses of copper and their reason (2)
- Electrical wire
- good conductor of electricity and malleable
- Water piper
- easy to work with and bent, non-toxic and unreactive with water
Alloy
A mixture of two or more metals or metal with a non-metal such as carbon
Metallic bonding
Metal atoms are held together strongly by metallic bonding in a giant metallic lattice wih delocalised electrons
* allows electrical conduction
* ductility and malleability as layers of atoms allows them to slide over each other
Brass (use)
An alloy of copper and zinc and is much stronger than either metal
* It is used in musical instruments, ornaments and door knobs
Stainless steel
Stainless steel is a mixture of iron and other elements, for example, chromium, nickel and carbon
* It is used in cutlery because of its hardness and resistance to corrosion
Why are metal alloys used more than pure metals?
- Alloys often have properties that can be very different from the metals they contain, for example, they can have more strength, hardness or resistance to corrosion or extreme temperatures
- These enhanced properties can make alloys more useful than pure metals
Iron and tungsten alloys (qualities)
Extremely hard and resistant to high temperatures
Iron and chromium or nickel alloy (qualities)
Resistant to corrosion
Reactivity series (from most to least reactive)
- Potassium
- Sodium
- Calcium
- Magnesium
- Aluminium
- Carbon
- Zinc
- Iron
- Hydrogen
- Copper
- Silver
- Gold
Describe the process of extraction of iron from hematite (8 steps)
- Raw materials iron ore (hematite), coke (impure form of carbon) and limestone are added into the top of the blast furnace
- Hot air is blown into the bottom
- At the bottom of the furnace:
- Coke burns in the hot air forming carbon dioxide
- Exothermic reaction heats the furnace: carbon + oxygen -› carbon dioxide
- Middle of the furnace:
- At the high temperatures in the furnace, more coke reacts with carbon dioxide forming carbon monoxide
- Carbon dioxide has been reduced to carbon monoxide: carbon + carbon dioxide -› carbon monoxide
- Top of the furnace:
- Carbon monoxide reduces the iron(III) oxide in the iron ore to form iron
- This will melt and collect at the bottom of the furnace, where it is tapped off: iron (III) oxide + carbon monoxide -› iron + carbon dioxide
- Limestone is added to the furnace to remove impurities because calcium cabonate in limestone thermally decomposes to form calcium oxide
- The calcium oxide formed reacts with the silicon dioxide, which is an impurity in the iron ore, to form calcium silicate
- This melts and collects as a molten slag floating on top of the molten iron, which is tapped off separately
Process of extraction of aluminium from bauxite (5 steps)
- Bauxite is purified to produce aluminium oxide (Al2O3)
- Aluminium oxide is the dissolved in molten cryolite
- this is because aluminium oxide has a melting point of over 2000°C which would use a lot of energy and be very expensive so they lower the melting point
- The mixture is placed in an electrolysis cell made from steel, lines with graphite
- The graphite lining acts as the negative electrode, with several large graphite blocks as the positive electrodes
- At the cathode:
- Aluminium gains electrons and molten aluminium forms at the bottom of the cell and then is siphoned off from time to time as fresh aluminium is added: Al3+ + 3e- → Al
- At the cathode:
- Oxide ions lose electrons and oxygen is produced: 2O2- → O2 + 4e-
