Overview
This lecture covers the structure and properties of two carbon allotropes—diamond and graphite—including their bonding, physical characteristics, and electrical conductivity.
Allotropes of Carbon
- Allotropes are different structural forms of the same element in the same physical state.
- Carbon has several allotropes, including diamond, graphite, graphene, and fullerenes.
- Both diamond and graphite are giant covalent structures, forming strong regular lattices.
Diamond Structure and Properties
- In diamond, each carbon atom forms four covalent bonds with other carbons in a 3D pattern.
- Diamond’s structure is very strong and requires a lot of energy to break, resulting in a high melting point.
- Diamond does not conduct electricity because it has no free electrons or ions.
Graphite Structure and Properties
- In graphite, each carbon atom is bonded to three others, creating hexagonal sheets.
- These sheets stack in layers held together by weak forces, allowing them to slide over each other, making graphite soft.
- Despite softness, graphite still has a high melting point due to strong covalent bonds within layers.
- Each carbon atom in graphite has one delocalized electron, which allows graphite to conduct electricity and heat.
Key Terms & Definitions
- Allotrope — Different structural forms of the same element in the same physical state.
- Giant covalent structure — A large lattice of atoms bonded by covalent bonds.
- Delocalized electron — An electron not tied to a particular atom, free to move within a structure.
- Graphene — A single layer of carbon atoms arranged in a hexagonal lattice, derived from graphite.
Action Items / Next Steps
- Review the differences in bonding and properties between diamond and graphite.
- Watch the next lecture for more on graphene and fullerenes.