ElementsWhy is sodium Na? Symbols that do not match the name
Most element symbols are easy to guess: H for hydrogen, Ca for calcium. Eleven are not. Their symbols come from older Latin names, or in one case a German name, that scientists across Europe already shared when symbols were fixed in the early 1800s.
| Symbol | English name | Older name | Meaning |
|---|---|---|---|
| Na | Sodium | natrium | from natron, a natural soda |
| K | Potassium | kalium | from an Arabic word for plant ashes |
| Fe | Iron | ferrum | Latin for iron |
| Cu | Copper | cuprum | the metal of Cyprus |
| Ag | Silver | argentum | Latin for silver, meaning bright or white |
| Sn | Tin | stannum | Latin for tin |
| Sb | Antimony | stibium | Latin name of its black mineral |
| W | Tungsten | wolfram | a German name, from the mineral wolframite |
| Au | Gold | aurum | Latin for gold |
| Hg | Mercury | hydrargyrum | Latinised Greek for liquid silver |
| Pb | Lead | plumbum | Latin for lead, the root of the word plumber |
Who chose the symbols?
The Swedish chemist Jöns Jacob Berzelius proposed the letter system in 1813 and 1814. Before that, chemists drew small pictures and circles, which were hard to print and to remember. Berzelius took one or two letters from each element's Latin name, because Latin was the common language of science.
Ways to remember them
- Fe: think of "ferrous" metals and "ferry" boats made of iron.
- Au: an "aura" is a golden glow.
- Ag: Argentina was named after silver.
- Pb: a plumber once worked with lead pipes.
- Na and K: learn them as a pair. Both are soft metals of group 1.
- Hg: "hydr" as in water, a liquid metal.
Names from places, people and planets
The symbols in the table above are odd because the name changed and the symbol did not. Many other elements have names with a story, even though the symbol matches. A single village in Sweden, Ytterby, gave its name to four elements found in the rock of its quarry: yttrium, ytterbium, terbium and erbium. Germanium, francium, polonium and americium honour countries and continents. Uranium, neptunium and plutonium follow the order of the outer planets as they were counted when the elements were named. Helium takes its name from the Greek word for the sun, because it was detected in sunlight before it was found on Earth. And a number of the heaviest elements are named after scientists, among them curium, einsteinium, mendelevium and bohrium.
Two spellings
Three elements are spelt differently in different countries. Indian and British books usually write aluminium and caesium, where American books write aluminum and cesium. For element 16 the international spelling is now sulfur, though sulphur is still common. The symbols Al, Cs and S are the same everywhere.
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