1. http://lawrencekok.blogspot.com Prepared by Lawrence Kok From : Tutorial on Allotropes of Carbon. https://www.youtube.com/watch?v=4XDJC64tDR0 COVALENT NETWORKS

2. Allotropes of Carbon different form of an element in the same physical state Diamond Fullerene, C60GrapheneGraphite

3. Allotropes of Carbon Diamond Fullerene, C60 Carbon- sp 2 hybridization 60 carbon atoms in sphere 1 π electron free to delocalized. Electrons NOT able to flow easily. Graphene Carbon- sp 2 hybridization Carbon bond to 3 others form hexagon (120°) Exist chicken wire/honeycomb- 1 layer Carbon- sp 3 hybridization Strong hard covalent network Carbon- sp 2 hybridization Strong covalent network within layers Weak Van Der Waals force bet layers Graphite Bond to 4 C atoms Bond to 3 C atoms …

4. Allotropes of Carbon Diamond Fullerene, C60 GrapheneGraphite

5. Allotropes of CarbonElement exist in different form/physical state Diamond Fullerene, C60 GrapheneGraphite Electrical conductivity Good - Within layer, - ONE free delocalized π electron Very Good - Within layer - ONE free delocalized π electron moving across the layer easily Poor - No free moving electron Semiconductor - Surface sphere, not planar - Some conductivity. - Lower electron mobility

6. Allotropes of CarbonElement exist in different form/physical state Diamond Fullerene, C60 GrapheneGraphite Electrical conductivity Special property Electrical conductivity Special property Good - Within layer - ONE free delocalized π electron Very Good - Within layer - ONE free delocalized π electron moving across the layer easily Poor - No free moving electron Semiconductor - Surface sphere, not planar - Some conductivity. - Lower electron mobility - Soft, layer slide across each other - Hardest substance - Jewellery Special property graphitelubricant electrode Lightest/strongest material replacing silicon in photovoltaic cell Drug delivery Transistor/Electronic Transparent conducting electrode Drug in graphene Potential medicinal use Drug delivery Target cancer cells Special property

7. Fullerene, C60 Graphene Click here to view touch screenhere Electron in hexagonal rings do not delocalized over whole molecule. Potential medicinal use Trap/bind drug inside/outside cage Target cancer cells Drug inside Drug bind outside Graphene touch screen and photovoltaic cell Click here for application of graphenehere Single sheet conductorRool into conductive nanotubes Electrical contact photovoltaic cell Lightest and strongest replacing silicon in photovoltaic cell Light and strong

8. Conduct current/heat very well Conduct current at speed of light Electron delocalized above/below plane High electron mobility Click here to viewhere sp 2 hybridization graphene rool into Carbon Nanotube (CNT) Click here TEDtalk graphenehere 1 layer thick Drug delivery to body Attachment drug therapeutics CNT = carbon nanotube

9. https://youtu.be/PiYnQLI-ufU SiliconSilicon dioxide

10. Silicon - sp 3 hybridization Giant lattice structure = covalent network Semiconductor Cannot form multiple bond ( larger size than C) Silicon -sp 3 hybridization Strong Insoluble in water High melting point Non-conductor of electricity Silicon = Si Silicon dioxide = sand = quartz

11. Explain Silicon dioxide cannot compete with the diversity possible in organic chemistry. However, there is evidence that the first forms of life were forms of clay minerals that were probably based on the silicon atom.

12. Why giant covalent substances (like diamond or silicon dioxide – sand) have very high melting points. Lots (thousands, millions!) of atoms joined together by covalent bonds very strong bonds lots of bonds to be broken need a huge amount of energy/heat to break the bonds therefore a very high melting point