Carbon is a non-metal that forms a huge number of compounds. Its ability to form chains gives rise to organic chemistry, an important area for science exams.
Why Carbon Forms Many Compounds
- Catenation: carbon atoms link with each other to form long chains and rings.
- Tetravalency: carbon has four valence electrons and forms four covalent bonds.
- It forms strong, stable covalent bonds.
Allotropes of Carbon
- Diamond: hardest natural substance, does not conduct electricity.
- Graphite: soft, slippery, conducts electricity, used in pencils.
- Fullerene (Buckminsterfullerene, C60): ball-shaped molecule.
Hydrocarbons
Compounds of carbon and hydrogen are hydrocarbons. Saturated hydrocarbons (alkanes, single bonds) include methane (CH4). Unsaturated hydrocarbons have double or triple bonds, like ethene and ethyne.
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Functional Groups
- Alcohol: -OH group (ethanol).
- Carboxylic acid: -COOH group (acetic acid).
- Aldehyde: -CHO group.
Important Compounds
Ethanol is used in alcoholic drinks and as a fuel. Acetic acid (vinegar) is a carboxylic acid. Soap is the sodium or potassium salt of long-chain fatty acids and works by forming micelles.
Quick Revision Points
- Diamond is the hardest natural substance.
- Graphite conducts electricity and is used in pencils.
- Carbon shows catenation and tetravalency.
- Methane (CH4) is the simplest hydrocarbon.
- Alcohol group is -OH; acid group is -COOH.
- C60 fullerene is a third allotrope of carbon.
- Soap cleans by forming micelles.