01 Historical background
🧊 3D Tetrahedral Molecular Geometry & sp³ Hybridization of Methane (CH₄)
3D Scientific Model
Accurate 3D molecular visualization illustrating carbon sp³ hybridized orbital geometry with tetrahedral bond angle of 109.5°, demonstrating maximum electron-pair separation and minimum electrostatic repulsion.
- People have used substances from plants and animals since ancient times.
- The ancient Egyptians, for example, used natural dyes, drugs and resins in mummification and in colouring; some of the colours on their temples still shine today.
In 1806 Berzelius divided compounds into two groups:
- Organic compounds: those obtained from living things (plants and animals);
- Inorganic compounds: those from mineral sources in the earth.
He believed organic compounds were made by a "vital force" present only in living cells, so they could never be made in a laboratory.
- In 1828 the German chemist Wöhler destroyed this idea.
- He heated a solution of two inorganic substances, ammonium chloride and silver cyanate.
- The reaction first gives ammonium cyanate, which rearranges on heating to urea — a typical organic compound found in the urine of mammals:
AgCNO + NH₄Cl → AgCl↓ + NH₄CNO NH₄CNO (heat) → H₂N–CO–NH₂ (urea)
- This experiment is regarded as the birth of modern organic chemistry.
- Chemists soon prepared huge numbers of organic compounds in every field (drugs, dyes, plastics, fibres, perfumes), and most of the organic compounds made today have never existed in any living organism.
- So the old definition based on "source" had to be abandoned.