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| Pregunta | Respuesta |
| Complete the sentences: Giant covalent lattices are huge networks of ______________-bonded atoms (they're sometimes called __________________ structures). Carbon and silica atoms can form this type of structure as they can form ______ strong covalent bonds. Different forms of the same element in the same state are called ______________. | Giant covalent lattices are huge networks of COVALENTLY-bonded atoms (they're sometimes called MACROMOLECULAR structures). Carbon and silica atoms can form this type of structure as they can form FOUR strong covalent bonds. Different forms of the same element in the same state are called ALLOTROPES. |
| What are the 3 carbon allotropes? | Graphite Diamond Graphene |
| Describe the structure of graphite |
The carbon atoms in graphite are arranged in sheets of flat hexagons covalently bonded with three bonds each. The fourth outer electron of each carbon atom is delocalised. The sheets of hexagons are bonded together by weak London forces
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| Describe and explain the properties of graphite | Sheets can slide over each other (weak forces between layers are easily broken) Conducts electricity (delocalised electrons) Low density (layers are quite far apart compared to the length of the covalent bonds) Very high melting point (strong covalent bonds) - over 3900K Insoluble in any solvent |
| What are the uses of graphite? | Dry lubricant or pencils (sheets can slide over each other) Strong, lightweight sports equipment (low density) |
| Describe the structure of diamond |
Each carbon atom is covalently bonded to four other carbon atoms. The atoms arrange themselves in a tetrahedral shape - it's crystal lattice structure
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| Describe and explain the properties of diamond | Very high melting point - over 3800K Extremely hard Good thermal conductor (vibrations travel easily through stiff lattice) Cannot conduct electricity (all outer electrons are held in localised bonds) Insoluble in any solvent |
| What are the uses of diamond in industry? | Drills and saws |
| TRUE OR FALSE: Silicon makes a crystal lattice structure like diamond and has similar properties | TRUE Each silicon atom can also form four strong, covalent bonds |
| Describe the structure of graphene |
Graphene is just one layer of graphite. The sheet is one atom thick, making it a 2D compound
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| Describe and explain the properties of graphene | Best known electrical conductor (delocalised electrons can move quickly above and below the sheet without layers) Extremely strong (delocalised electrons strengthen the covalent bonds between carbon atoms) Transparent and incredibly light (single layer) |
| What are the uses of graphene? | Potential applications in high-speed electronics and aircraft technology (high strength, low mass and good electrical conductivity) Potentially useful material for touchscreens on smartphones and other electrical devices (flexibility and transparency) |
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