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Title: GCSE Chemistry 2.1 - Bonding
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A*.) This is one of six topics in the unit.
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A*.) This is one of six topics in the unit.
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2
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g
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g
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This is because Na +
and Cl- have fewer charges than Mg2+ and O2-, and Na+ ions are larger than Mg2+ ions
and cannot get as close to the negatively charged ions
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g
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1
Ionic bonding
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moved electrons
Covalent bonding
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shared electrons
Diamond
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contains strong covalent bonds, where each carbon is bonded to four others, forming a giant
covalent structure
high melting point (a result of the strong covalent bonding present)
hard, brittle, does not conduct electricity (because there are four bonds)
Graphite
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contains strong covalent bonds, where each carbon is bonded to three others, forming
layers than can slide over each other
high melting point (a result of the strong covalent bonding present)
soft, greasy, conducts electricity (because there is a fourth ‘delocalised’ electron
Graphene
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shown to be the strongest material ever tested and the best electrical conductor, but,
although claims have been made that it will transform technology in the future, there are, as
yet, no commercially available 'graphene products'
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Bulk materials
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do not have the same properties as individual atoms, as demonstrated by diamond,
graphite, fullerenes, carbon nano-tubes and graphene having different properties despite all
containing only carbon atoms and by nano-scale silver particles exhibiting properties not
seen in bulk silver
3
Nano-scale particles of silver
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antibacterial, antiviral and antifungal
used in plasters, antiseptic sprays, refrigerator linings, socks and deodorant sprays
Nano-scale particles of titanium dioxide
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absorb and reflect UV light, but are also transparent so appeal to users
used in some sun screens
catalyse the breakdown of dirt in the presence of UV light
cause water to spread out in a thin film rather than form droplets on the surface
used in self-cleaning glass
The possible risks associated with the use of nano-scale particles of silver and titanium
dioxide, and of potential future developments in nanoscience
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Nanomaterials currently used have been tested to ensure that they cause no
damage to individuals or the environment, but that their long-term effects are as yet
unknown
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While it has been shown that these uses are safe in the short term, there is no
certainty that exposure over many years will not result in problems
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Title: GCSE Chemistry 2.1 - Bonding
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A*.) This is one of six topics in the unit.
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A*.) This is one of six topics in the unit.