Every element has a one- or two-letter symbol. Most are easy: the first letter or two of the English name. The first 20 are worth knowing by heart, because they come up constantly.
How symbols are written
- The first letter is always a capital; a second letter is always lowercase.
- That matters: Co is cobalt, but CO is carbon monoxide, a compound of carbon and oxygen.
The first 20, in order
H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca.
A trick many students use is to learn them in groups of five, out loud, like a phone number.
The ones that come from Latin
When a symbol doesn't match the English name, the answer is usually Latin:
| Symbol | Element | Latin |
|---|---|---|
| Na | sodium | natrium |
| K | potassium | kalium |
| Fe | iron | ferrum |
| Cu | copper | cuprum |
| Ag | silver | argentum |
| Au | gold | aurum |
| Sn | tin | stannum |
| Pb | lead | plumbum |
| Hg | mercury | hydrargyrum |
Some English words keep the Latin too: ferrous metals contain iron, and a plumber is named after lead pipes.
Watch out for
S is sulfur and Si is silicon, not silver. Au is gold, Ag is silver.