Organic chemistry is the branch of chemistry that studies carbon-containing compounds—especially those that also contain hydrogen. These compounds are known as organic compounds, and they form the basis of life on Earth. Organic chemistry focuses on their structures, properties, reactions, preparation methods, and applications.
Carbon is special because:
Carbon atoms can bond with one another to form:
Long chains
Branched chains
Rings
This allows millions of different molecules to exist.
Carbon has four valence electrons, allowing it to form stable covalent bonds with:
Hydrogen
Oxygen
Nitrogen
Halogens
Sulfur
Other carbon atoms
This versatility makes carbon the foundation for complex molecules like proteins, DNA, plastics, and fuels.
Carbon forms strong C–C and C–H bonds, making organic molecules stable.
| Organic Chemistry | Inorganic Chemistry |
|---|---|
| Studies carbon compounds (except CO₂, CO, carbonates, etc.) | Studies all other elements and compounds |
| Mostly covalent compounds | Mostly ionic compounds |
| Low melting and boiling points | Often high melting points |
| Often flammable | Usually non-flammable |
| Soluble in organic solvents | Soluble in water |
Organic compounds are grouped into families called homologous series, each with similar chemical properties.
Some major classes include:
Compounds containing only hydrogen and carbon.
Alkanes (single bonds)
Alkenes (double bonds)
Alkynes (triple bonds)
Arenes (aromatic compounds)
Contain the –OH (hydroxyl) group.
Contain carbonyl groups (C=O).
Contain the –COOH group.
Formed from alcohols and acids; responsible for fruity smells.
Contain nitrogen; found in proteins and pharmaceuticals.
Organic molecules can be represented in different ways:
Molecular formulas (e.g., C₂H₆O)
Structural formulas (showing how atoms bond)
Displayed formulas
Condensed formulas
Skeletal formulas (lines represent carbon chains)
Isomers are compounds with the same molecular formula but different structures or arrangements.
Main types:
Structural isomerism
Chain isomers
Position isomers
Functional group isomers
Stereoisomerism
Geometric (cis/trans)
Optical isomerism
Isomerism explains why organic chemistry is extremely diverse.
Plants (carbohydrates, oils, alkaloids)
Animals (proteins, fats)
Fossil fuels (petroleum, natural gas, coal)
Plastics
Medicines
Dyes
Detergents
Pesticides
Organic chemistry is crucial in many areas of life and industry:
Drugs, antibiotics, vaccines.
Pesticides, fertilizers, herbicides.
Fuel, lubricants, kerosene, diesel.
Flavors, preservatives, sweeteners.
Plastics, nylon, polyester, PVC.
Creams, perfumes, soaps, shampoos.
Organic chemistry is the study of carbon compounds—an enormous and essential area of chemistry. Its importance is seen in nature, industry, medicine, and everyday life. Because of carbon’s unique bonding abilities, organic chemistry is one of the most diverse and foundational sciences, connecting biology, materials science, and environmental studies.