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Mono, di, tri, tetra… these little prefixes tell you exactly how many atoms of each element are hiding in a compound’s name.
- First element keeps its name; the second ends in -ide .
- Prefixes show the count: mono-(1), di-(2), tri-(3), tetra-(4), penta-(5), hexa-(6) .
- mono- is usually dropped for the first element (e.g. CO = carbon monoxide).
- No prefix before hydrogen as first element (H₂S = hydrogen sulfide).
Examples: CO₂ = carbon dioxide, CS₂ = carbon disulfide, PCl₃ = phosphorus trichloride, SF₆ = sulfur hexafluoride, N₂O₄ = dinitrogen tetroxide, N₂O₅ = dinitrogen pentoxide. Some are known by common names — H₂O as water, NH₃ as ammonia.
- -ide ending — the ending given to the second (non-metal) element in a compound name.
- Prefix system — mono, di, tri, tetra… used to show the number of atoms of each element.
Atoms can release enormous energy when their nuclei split or combine — nuclear energy. In nuclear power plants this heat drives turbines to generate electricity, a cleaner alternative to fossil fuels, and is also used in medicine and research. In India, scientists like Raja Ramanna made major contributions to the nation’s Nuclear Energy Programme and its peaceful use.
