Carbon Allotropes: Graphite, Diamond, Graphene, Fullerenes and Carbon Nanotubes
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1. Graphite
Graphite: Preparation, Properties, Structure and Uses
Graphite PYQs MCQs
2. Diamond
Diamond: Preparation, Properties, Structure and Uses
Diamond PYQs MCQs
3. Graphene
Graphene: Preparation, Properties, Structure and Uses
Graphene PYQs MCQs
4. Fullerenes
Fullerenes: Preparation, Properties, Structure and Uses
Fullerenes PYQs MCQs
5. Carbon Nanotubes
Carbon Nanotubes: Preparation, Properties, Structure and Uses
Carbon Nanotubes PYQs MCQs
Ultimate Comparison Table of Carbon Allotropes (High-Weightage for All Exams)
| Property | Diamond | Graphite | Fullerene (C60) | Graphene | Carbon Nanotubes (CNTs) |
|---|---|---|---|---|---|
| Dimensionality | 3D | 2D layers (3D crystal) | 0D (molecule) | 2D sheet | 1D |
| Hybridisation | sp³ | sp² | sp² (curved) | sp² | sp² (rolled) |
| Structure | Tetrahedral 3D network | Hexagonal layers | 12 pentagons + 20 hexagons | Single honeycomb sheet | Rolled graphene cylinder |
| Discovery | Ancient | Ancient | 1985 (Kroto, Curl, Smalley) | 2004 (Geim & Novoselov) | 1991 (Sumio Iijima) |
| Density (g/cm³) | 3.51 | 2.26 | 1.72 | ~2.2 (theoretical) | 1.3–1.4 |
| Hardness (Mohs) | 10 (hardest) | 1–2 (soft) | Soft | — (strongest material) | Extremely strong fibre |
| Tensile Strength | High (brittle) | Low | Moderate | ~130 GPa (highest known) | ~100–200 GPa |
| Young’s Modulus | ~1050 GPa | ~1000 GPa (in-plane) | — | ~1 TPa | ~1 TPa |
| Electrical Conductivity | Insulator | Good (in-plane) | Insulator → superconductor when doped | Best known conductor | Metallic or semiconducting (chirality dependent) |
| Thermal Conductivity (W/m·K) | ~2000–2200 | ~200–2000 (in-plane) | ~0.4 | ~5000 | ~3500 (SWCNT) |
| Band Gap | 5.5 eV (insulator) | 0 eV (semi-metal) | ~1.8 eV | 0 eV (semi-metal) | 0 or up to ~1 eV (depends on chirality) |
| Transparency | Transparent | Opaque | Coloured solutions | 97.7% transparent | Semi-transparent |
| Thermodynamic Stability (RTP) | Metastable | Most stable | Metastable | Metastable | Metastable |
| Major Uses | Cutting tools, jewellery, heat sinks | Pencils, lubricants, electrodes | Superconductors, drug delivery | Transparent conductors, sensors, batteries | Composites, electronics, space elevator |
| Typical Exam Question Tag | Hardest natural substance | Soft, conductor | Superconductivity in K3C60 | Highest thermal & electrical conductivity | Strongest material, ballistic conduction |