In high school we were taught that the formula for pH is the negative of the common logarithm of hydrogen ion concentration: pH = -log[H+].
It wasn't until I took organic chemistry that the "acid dissociation constant" (pKa) was introduced. It was at that point that the textbook explained that "p" was used as a mathematical operator, meaning the negative of the common logarithm. (See https://web.mst.edu/~gbert/logs/pH.html.)
Why didn't they teach us that in high school? There would have been no rote memorization of the pH formula: the equation is right there in the name!
Is this operator restricted to chemistry? I've never seen it used in a (purely) mathematical context and have always wondered how the usage originated. Does anyone know its etymology or the first time it appeared in a publication?