🔬 Introduction to Carbon
- Carbon is a non-metal in Group IV of the Periodic Table.
- Atomic number: 6; Electron configuration: 2,4
- It can form four covalent bonds due to 4 valence electrons.
- Carbon forms a vast number of compounds (organic and inorganic) because of its ability to:
- Catenate (form chains with itself)
- Form strong covalent bonds with many elements
- Exist in multiple allotropes
🧱 Allotropes of Carbon
Allotropes are different forms of the same element in the same physical state.
1️⃣ Diamond
🧬 Structure:
- Each carbon atom is covalently bonded to 4 other carbon atoms in a tetrahedral arrangement.
- Forms a 3D giant covalent structure (network lattice).
⚙️ Properties:
- Very hard (hardest natural substance) 🔨
- High melting and boiling points
- Does not conduct electricity (no free electrons)
- Transparent and lustrous
🛠 Uses:
- Cutting tools
- Drill bits
- Jewelry
2️⃣ Graphite
🧬 Structure:
- Each carbon atom is bonded to 3 other carbon atoms in layers forming hexagonal rings.
- The 4th electron is delocalized, allowing electrical conductivity.
- Layers are held by weak van der Waals forces, so they slide over each other.
⚙️ Properties:
- Soft and slippery
- Conducts electricity
- High melting point
- Grey-black and opaque
🛠 Uses:
- Pencil lead
- Lubricants
- Electrodes in batteries
3️⃣ Fullerenes (C₆₀ – Buckminsterfullerene)
🧬 Structure:
- Molecular form of carbon, not a giant structure.
- Carbon atoms are arranged in pentagons and hexagons, forming a spherical cage (like a football).
- Consists of 60 carbon atoms.
⚙️ Properties:
- Soft
- Low melting point
- Can accept and donate electrons
- Poor conductor (some derivatives conduct)
🛠 Uses:
- Drug delivery in medicine
- Lubricants
- Nanotechnology
4️⃣ Graphene (Extension beyond syllabus, but useful)
🧬 Structure:
- A single layer of carbon atoms in a hexagonal pattern.
- Like a single sheet of graphite.
⚙️ Properties:
- Very strong
- Excellent conductor of heat and electricity
- Lightweight and flexible
🛠 Uses:
- Flexible electronics
- Conductive coatings
- Solar cells
5️⃣ Carbon Nanotubes (Mentioned for awareness)
🧬 Structure:
- Cylindrical fullerenes; rolled sheets of graphene.
- Can be single-walled or multi-walled.
⚙️ Properties:
- High tensile strength
- Excellent electrical conductivity
🛠 Uses:
- Nanomedicine
- Electronics
- Reinforcing materials
🔄 Comparison of Allotropes (Summary Table)
| Property | Diamond | Graphite | Fullerene (C₆₀) |
|---|---|---|---|
| Structure | 3D tetrahedral | Layered hexagons | Spherical molecules |
| Bonding | 4 covalent bonds | 3 covalent + delocalized e⁻ | 3 covalent bonds per atom |
| Hardness | Very hard | Soft | Soft |
| Conductivity | No | Yes | Poor |
| Melting Point | Very high | High | Low |
| Use | Tools, jewelry | Electrodes, lubricant | Drug delivery, nano tech |
📝 Sample Questions and Answers
Q1: Why does diamond not conduct electricity?
Answer: In diamond, all 4 outer electrons of each carbon atom are used in covalent bonding, so there are no free electrons to carry an electric current.
Q2: Why is graphite slippery?
Answer: Graphite has layers of carbon atoms that can slide over each other because of weak forces between the layers, making it slippery.
Q3: What makes fullerenes useful in medicine?
Answer: Fullerenes have a hollow structure that can carry drug molecules inside, making them useful for targeted drug delivery.
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