Properties of giant ionic lattice
- conducts electricity when molten, doesn’t conduct electricity when solid (the ions are held in fixed positions in the lattice so cannot move to carry a charge when solid, however when molten the ions are free to move and carry a charge)
- high melting and boiling points (large amount of energy is required to break the strong ionic bonds between the ions in the lattice)
- soluble in water
- is a compound
Properties of a covalent molecular structure
- low melting and boiling points (a small amount of energy is needed to break the weak van der Waals forces between the molecules
- insoluble in water
- does not conduct electricity (the molecules are neutral so there are no ions or delocalised electrons to carry a charge)
Properties of a giant metallic structure
- high melting point (a large amount of energy is required to break the strong metallic bonds between the positive ions and delocalised electrons)
- conducts electricity (delocalised electrons can move and carry a charge)
- ductile and malleable (layers can slide over each other without disrupting the bonding)
What are the sub categories of the giant covalent structure?
Diamond, graphene and graphite
Properties of diamond
GIANT COVALENT STRUCTURE (each carbon is covalently bonded to four other carbon atoms in a tetrahedral 3D structure
- high melting and boiling points (a large amount of energy is needed to break the strong covalent bond between the carbon atoms)
- doesn’t conduct electricity (diamond has no ions or delocalised electrons that can carry charge)
- very hard (strong covalent bonds arranged in a rigid tetrahedral structure)
- used for drilling through hard materials like rock and glass
Properties of graphene
- conducts electricity (has free electrons to carry a charge)
- used in batteries and solar cells
- a single atom thick layer of graphite (arranged in hexagons)
- 100x stronger than steel (due to rigid structure of hexagons and strong covalent bonds)
- low density (single layer of atoms)
Properties of graphite
GIANT COVALENT STRUCTURE (each carbon atom forms three covalent bonds with other carbon atoms, arranged in hexagons, weak forces of attraction between layers caused by delocalised electrons)
- conducts electricity (carbon atoms have a free electron which can carry a charge)
- high melting and boiling points (a large amount of energy is required to break the strong covalent bonds between carbon atoms)
- soft (weak forces between the layers so they can easily slide over each other)
- used in pencils and as a lubricant
Allotrope
Different forms of the same element in the same physical state (eg carbon —> graphite, graphene, diamond)
Ductile
Can be drawn into wires
Malleable
Can be hammered into shape
Alloy
A mixture of two or more elements, at least one of which is a metal and the resulting mixture has metallic properties
Why is pure gold seldom used in jewellery?
Too soft
What is used instead of pure gold in jewellery?
A gold alloy containing silver, copper or zinc
What is the purity of gold measured in?
Carats
How many carats is pure gold?
24
Equation for % of gold in an alloy
No. Of carats/ 24 x 100
How many carats indicates 75% gold?
18
How do alloys affect metallic structure?
The different sizes of atoms in an alloy distort the layers in metallic structure, making it more difficult for them to slide over each other. This means alloys are harder than pure metals
How man covalent bonds can carbon form?
4
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Topic 1 Atomic Structure27
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Topic 2 Bonding18
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Topic 3 Structure19
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Topic 4 Nanoparticles13
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Topic 5 Structures, Formulae And Equations29
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Topic 8 Acids, Bases And Salts36
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1.6 Periodic Table40
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Topic 7 Quantitative Chemistry21
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1.9 Chemical Analysis59
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Topic 10 Solubility12
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2.1 Metals And Reactivity Series40
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2.3 Rates Of Reaction22
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2.5 Organic Chemistry83
