Question

Why are the properties of diamond very different from those of graphite although both are the different forms of the same substance?

Answer 1

Although diamond and graphite are both made of carbon atoms, they have very different physical properties because of the different ways the atoms are arranged (different structures).

1. Diamond and graphite are allotropes of carbon, meaning they are made of the same element (carbon) but have different structures, which lead to different properties.
2. Diamond is hard, non-conductive, and used as an abrasive.
3. Graphite is soft, conductive, and used as a lubricant and in pencils.
4. This makes diamond have a high melting point while the fourth electron is free (delocalized) and moves between layers, making graphite a good conductor of electricity.
5. Each carbon atom forms four strong covalent bonds with other carbon atoms in a 3D tetrahedral structure, while it is bonded to three other carbon atoms in flat hexagonal layers.
6. Weak forces hold the layers together, allowing them to slide over each other, resulting in graphite’s soft and slippery nature.