How the character is built
The 钅 radical marks this as a metal, and that is not a coincidence of this one character — it holds right across the table. Read the radical first and the element's state at room temperature is already settled. It is 金 (jīn) squeezed into the space beside another component — radicals change shape by position, which is why 金 is hard to spot until you know to look for 钅.
The 金 metal radical plus the phonetic 甲 jiǎ, the same 甲 as in 甲骨文 'oracle bone script'.
Where you actually meet it
钾肥 (jiǎféi) potash fertiliser
The element itself
Potassium metal is soft enough to be cut like cheese and reacts with water even more energetically than sodium. Its commercial form is potash, mined from evaporite beds hundreds of metres down in Saskatchewan and northern Europe where ancient seas dried out, the potassium salts crystallising last because they are the most soluble. Potassium is also mildly radioactive in a way nothing can avoid — that same potassium-40 — so every banana, and every person, gives off a faint and entirely harmless count.
Where it sits among the 118
First isolated in 1807.
In living things
Potassium is the ion inside the cell, held there at maybe thirty times its outside concentration, and the resting voltage across every membrane in your body is essentially potassium's tendency to leak back out. A nerve impulse briefly opens the gates — but only a vanishing fraction of the ions actually move, so the gradient itself is barely dented by a single spike; the pump simply tops it back up afterwards. Plants use the same ion mechanically: guard cells take up potassium, water follows by osmosis, they swell, and the pore between them opens, which is how a leaf breathes.
In Chinese history and language
Saltpetre, 硝石 xiāoshí, is the oxidiser that makes gunpowder work, and telling it apart from the other white crystalline salts sold under confusingly similar names was the central practical problem of early Chinese chemistry. Around the end of the fifth century the pharmacologist Tao Hongjing wrote down the test that separates them: burn a little, and the genuine article throws off a purple-blue flare. It did not end the confusion — the drug markets went on muddling the white salts for centuries — but the colour he described is the potassium line, seen and recorded more than a thousand years before there was anything to call it.
Where it comes from in China
China has almost no marine potash. The world's great potash supplies are buried evaporite beds in Canada, Russia and Belarus, and Chinese geology never provided one — so its potassium comes instead from salt lakes, pumped into evaporation ponds at Qarhan in Qinghai and at Lop Nur, the dry lake in eastern Xinjiang. Both are basins with no outlet to the sea, where inland drainage has been quietly concentrating salts for a very long time.
The full entry
For stroke order, example sentences, audio and the complete set of meanings, see the dictionary entry.
钾Potassium in the dictionary →Others built the same way
Every one of these carries 钅, and every one is a metal.