Is there a rule whether a compound word is hyphenated (at a line break) between its components?
potash is hyphenated as
potassium is hyphenated as
From Merriam Webster:
Origin of POTASSIUM
New Latin, from potassa potash, from English potash
Why is potassium not hyphenated
pot-as-si-um, which would preserve the sense?
Is there some general rule about this?