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Most element symbols are easy: H for hydrogen, O for oxygen, Ca for calcium. Then you meet sodium (Na), potassium (K) and iron (Fe), and it feels like a trick. It isn’t. These symbols come from the element’s name in another language — mostly Latin — and they were standardized before the English names became common.
Why Latin?
The Swedish chemist Jöns Jacob Berzelius introduced the modern system of one- or two-letter symbols around 1813–1814, replacing older alchemical pictograms. Latin was still the international language of science, so he based many symbols on Latin names. The system was so practical that it spread worldwide, and those Latin-derived symbols stuck even as everyday names changed.
The full list
| Symbol | Element | Origin |
|---|---|---|
| Na | Sodium | Latin natrium (from natron, a sodium carbonate mineral) |
| K | Potassium | Latin kalium (from Arabic al-qalī, plant ashes) |
| Fe | Iron | Latin ferrum |
| Cu | Copper | Latin cuprum (from Cyprus) |
| Ag | Silver | Latin argentum |
| Sn | Tin | Latin stannum |
| Sb | Antimony | Latin stibium |
| Au | Gold | Latin aurum |
| Hg | Mercury | Latinized Greek hydrargyrum, “liquid silver” |
| Pb | Lead | Latin plumbum |
| W | Tungsten | German Wolfram |
That’s eleven. A few others look odd too, but for different reasons:
- Hg for mercury comes from hydrargyrum, but the English name “mercury” comes from the planet and the Roman god — alchemists linked the fast-moving liquid metal with the fast-moving planet.
- W for tungsten comes from wolfram, the name used in German and many other languages (and still preferred in some). “Tungsten” is Swedish for “heavy stone”.
Memory tips
- Na — “natron” was used by ancient Egyptians in mummification; think “Na-tural salt”.
- K — kalium is still the name for potassium in German, Dutch and several other languages.
- Fe — think ferrous and ferric, and ferromagnetic.
- Cu — cupric and cuprous; “Cu” for copper from Cyprus.
- Ag — Argentina was named for silver (argentum); think “Argentina’s Silver”.
- Au — aurum, related to “aurora”, the golden glow of dawn.
- Pb — plumbum gives us “plumbing” and “plumb line” (a lead weight on a string).
- Hg — “Hydrargyrum”, water-silver, a liquid metal.
- Sn — stannum; “stannous fluoride” is in some toothpastes.
- Sb — stibium, from an ancient word for the antimony-based cosmetic kohl.
- W — “Wolfram” — the metal in old light bulb filaments.
Symbols that come from other people’s names or places
A few symbols match their names, but the names themselves are surprising. Yttrium, terbium, erbium and ytterbium all come from one Swedish village, Ytterby. See how elements get their names.
Why the symbols matter
Symbols are the same in every language. A chemist in Japan, Brazil and Germany will all write NaCl for table salt, even though the element is called natorium, sódio and Natrium in their languages. That universal shorthand is what makes chemical formulas an international language.
Rules for symbols today
- The first letter is always a capital; any second letter is lowercase. Co is cobalt; CO is carbon monoxide.
- Symbols for new elements are proposed along with their names and approved by IUPAC. Before approval, elements used temporary three-letter symbols (like Uuo for ununoctium, now Og).
Quick answers
Why is sodium’s symbol Na? From its Latin name, natrium.
Why is potassium K? From its Latin name, kalium.
Why is gold Au? From aurum, the Latin for gold.
Test yourself
Hover over or click any element on the interactive periodic table to check its symbol, name and atomic number.
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