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Carbon and Its Allotropes

General Properties of Carbon

• Carbon forms the maximum number of compounds among all elements.
• Substances containing carbon: Diamond, Graphite, Coal, Lignite.
• Substances not containing carbon: Sand, Tin, Silver, Iron.

Allotropes of Carbon (Forms of Pure Carbon)

• Primary/Well-Known Allotropes:
  • Diamond:
    • Hardest natural material.
    • Crystalline in form.
    • Can scratch or etch glass.
    • Unit of weight is a carat (1 carat = 200 mg).
  • Graphite:
    • Crystalline form of carbon.
    • Used as a lubricant in heavy machines.
    • Good conductor of electricity.
    • Used in pencil leads.
• Additional/Novel Allotropes:
  • Fullerene: The third major allotrope discovered.
  • Graphene:
    • A nanostructure and two-dimensional material.
    • Composed purely of carbon atoms (an allotrope, not an alloy or isotope).
    • One of the thinnest but strongest materials known (stronger than steel, brass, german silver).
    • Has excellent electrical conductivity.
    • Used as ‘conducting electrodes’ in touchscreens, LCDs, and organic LEDs.
    • It is not made of silicon.
  • Oxocarbon: Also recognized as a form of carbon.

Discovery, Synthesis, and Composition

Discovery of Fullerenes

• The Nobel Prize-winning discovery team consisted of H.W. Kroto, R.F. Curl, and R.E. Smalley.
• Note: Faimen was not part of the team.

Chronological Order of First Lab Synthesis

• The correct order is: Kevlar → Fullerene → Graphene → Black gold.

Composition of Specific Substances

• Substances made of carbon only: Diamond, Graphite, Graphene.
• Substances NOT made of carbon only:
  • Kevlar, Lexan: Synthetic polymers.
  • Spider silk, Keratin: Proteins.
  • These contain other elements besides carbon.

Coal and Carbon Content

Types of Coal (by Increasing Carbon Content)

• The order of increasing carbon percentage is: Peat → Lignite → Bituminous → Anthracite.
• Anthracite has the highest percentage of carbon.

Carbon in Iron and Steel

• Pig Iron contains the highest amount of carbon among iron/steel products.
• Wrought iron has a very low carbon content.

Other Important Substances and Facts

Crystals

• Crystalline substances: Diamond, Quartz, Graphite.
• Non-crystalline substance: Sulphur (in the context of the given question).

Glass Etching/Scratching

• Glass can be etched or scratched by:
  1. Diamond (due to its hardness).
  2. Hydrofluoric Acid (due to a chemical reaction).

Gases and Ice

• Dry Ice: Solid form of Carbon Dioxide (CO₂).
• Water Gas: A mixture of Carbon Monoxide and Hydrogen (CO + H₂).
• Gas from Soda Water: Carbon Dioxide (CO₂).

Chemical Bonds

• The bond order of the CO (Carbon Monoxide) group is 3.

Miscellaneous Facts

• Water Hardness: Caused by the presence of Calcium Sulphate.
• Air Composition: Oxygen is the main component of air.
• Nitrogen Use: Used in the manufacture of vegetable ghee (hydrogenation process).

Common Misconceptions and Correct Matches

Incorrectly Matched Pair

• Fullerene is not an “Organic compound containing fluorine” or a “Fluorine-containing polymer.” It is an allotrope of carbon.

Correctly Matched Pairs (for Context)

• Dry Ice = Solid Carbon Dioxide.
• Mustard Gas = Poisonous liquid used in chemical warfare.
• Teflon = Polymer containing fluorine.
• Keratin = Protein found in the outer layer of human skin.

Know More About Carbon and its Various Forms:

• Carbon and its Various Forms – Old Year Questions
• Carbon and its Various Forms One Liner Questions & Answers