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Questions and Answers
Considering the electronic structure and bonding characteristics, which of the following allotropes of carbon would exhibit the highest electrical conductivity under standard conditions?
Considering the electronic structure and bonding characteristics, which of the following allotropes of carbon would exhibit the highest electrical conductivity under standard conditions?
- Buckminsterfullerene ($C_{60}$), because its spherical structure allows for maximum electron mobility across its surface.
- Amorphous carbon, due to its disordered structure creating numerous electron hopping sites.
- Diamond, due to its $sp^3$ hybridized carbon atoms forming a tetrahedral lattice with delocalized electrons.
- Graphite, owing to its $sp^2$ hybridized carbon atoms arranged in hexagonal layers with one delocalized electron per atom. (correct)
The high melting point of diamond is primarily attributed to strong intermolecular forces between carbon atoms.
The high melting point of diamond is primarily attributed to strong intermolecular forces between carbon atoms.
False (B)
Explain why the hardness of diamond is significantly greater than that of graphite, relating your answer to their respective atomic arrangements and bonding characteristics.
Explain why the hardness of diamond is significantly greater than that of graphite, relating your answer to their respective atomic arrangements and bonding characteristics.
Diamond possesses a three-dimensional tetrahedral network of covalently bonded carbon atoms, providing uniform resistance to deformation in all directions. Graphite, conversely, consists of weakly bonded layers, facilitating easy slippage and resulting in lower hardness.
The ability of graphite to act as a lubricant is primarily attributed to its ______ structure, which allows layers to slide easily over one another.
The ability of graphite to act as a lubricant is primarily attributed to its ______ structure, which allows layers to slide easily over one another.
Match the following carbon allotropes with their corresponding structural features:
Match the following carbon allotropes with their corresponding structural features:
Considering the properties of silicon dioxide ($SiO_2$), which of the following applications would NOT be suitable?
Considering the properties of silicon dioxide ($SiO_2$), which of the following applications would NOT be suitable?
The electrical conductivity of silicon dioxide ($SiO_2$) is comparable to that of graphite due to the presence of delocalized electrons in its structure.
The electrical conductivity of silicon dioxide ($SiO_2$) is comparable to that of graphite due to the presence of delocalized electrons in its structure.
Describe the primary reason for the difference in melting points between diamond (above 3700°C) and silicon dioxide (above 1630°C), despite both having giant covalent structures.
Describe the primary reason for the difference in melting points between diamond (above 3700°C) and silicon dioxide (above 1630°C), despite both having giant covalent structures.
The primary reason buckminsterfullerene ($C_{60}$) is used as a lubricant is because of its weak ______ forces between molecules, allowing it to be slippery.
The primary reason buckminsterfullerene ($C_{60}$) is used as a lubricant is because of its weak ______ forces between molecules, allowing it to be slippery.
In the context of materials science, which characteristic is most directly responsible for diamond's exceptional ability to conduct heat?
In the context of materials science, which characteristic is most directly responsible for diamond's exceptional ability to conduct heat?
Flashcards
Allotrope
Allotrope
The existence of a chemical element in two or more forms, which may differ in arrangement of atoms or molecules.
Diamond Structure
Diamond Structure
A strong, rigid three-dimensional structure with an infinite network of carbon atoms.
Diamond's Electrical Conductivity
Diamond's Electrical Conductivity
Diamond is a non-conductive material due to the absence of free electrons.
Graphite Structure
Graphite Structure
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Graphite's Electrical Conductivity
Graphite's Electrical Conductivity
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Fullerene C60 Structure
Fullerene C60 Structure
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Structure of Silicon(IV)Oxide
Structure of Silicon(IV)Oxide
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Electrical Conductivity of Silicon (IV) Oxide
Electrical Conductivity of Silicon (IV) Oxide
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Study Notes
- Allotropes are different forms of a chemical element, varying in atom arrangement or molecule composition.
- Allotropes share the same chemical properties, but may have different physical properties.
- Carbon allotropes include diamond, graphite, and fullerenes.
Diamond
- Carbon atoms arrange tetrahedrally, each bonded to four others.
- Diamond has a strong, rigid, three-dimensional network of carbon atoms.
- Diamond acts as an electrical insulator due to lack of free electrons.
- The melting point is above 3700°C due to the strong covalent bonds.
- Diamond is insoluble in water and organic solvents.
- Diamond demonstrates good heat conductivity because of strong lattice vibrations.
- Diamond is extremely hard and transparent.
- Uses include jewellery, cutting tool coatings, diamond-tipped tools.
- Diamond is the ultimate abrasive, capable of polishing hard surfaces.
Graphite
- Graphite is soft, whereas diamond is hard.
- Graphite is an electrical conductor, diamond is an insulator.
- In graphite, carbon atoms link to three others in hexagonal arrays on a plane.
- Each carbon atom has one free electron.
- There is little connectivity between planes, so graphite is made of flat surfaces that slide easily.
- Graphite is a good electrical conductor with each carbon atom having a non-bonded outer electron that becomes delocalized.
- Graphite is insoluble in water and organic solvents.
- Graphite demonstrates good heat conductivity due to free electrons and lattice vibrations.
- Graphite is soft because the bonds between layers are weaker than covalent bonds.
- Graphite has an opaque, greyish black appearance.
- Graphite is a good lubricant and useful for electrodes.
Fullerenes (Buckyballs)
- Fullerenes are carbon allotropes forming hollow tubes or spheres.
- A C60 structure consists of 60 carbon atoms linked in a cage-like structure similar to a soccer ball.
- Fullerene is a good, but not great, electrical conductor.
- It sublimes at approximately 600°C.
- It is sparingly soluble in organic solvents/carbon disulfide, insoluble in water.
- It is soft because of weak intermolecular forces between carbon atoms.
- Fullerenes appear as shiny black needle-like crystals.
- Fullerenes are slippery and used as lubricants.
Silicon (IV) Oxide (SiO2)
- Composed of a giant covalent structure similar to diamond, with a tetrahedral arrangement.
- It is an electrical insulator.
- The melting point is above 1630°C.
- SiO2 is insoluble in water.
- It has very hard properties.
- SiO2 appear as a white or colorless crystalline compound.
- Found mainly as quartz, sand, and other minerals.
- Used for glass, ceramic and cement production, and as a reinforcing agent in rubber and plastic.
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