Potassium.
Potassium is kalium in Latin.
The original word for potassium in Latin is kalium. That is where you get K for the element , Potassium.
Potassium's chemical symbol K comes from the Latin word kalium.
Most of the atomic symbols come from the Latin names for the elements. The Latin name for potassium is 'kalium'
The element sodium comes from the Latin word "natrium."
In Latin, sodium is natrium, hence the Na symbol.
Latin, Greek and proper noun derivatives
It is only a convention.
Silver. Incidentally, gold is Au. Both, I believe, come from the Latin roots of the word gold in Latin: "aurum"
The word alkali come from the language Arabic
The word "alkali" comes from the Arabic word "al-qalīy" which means "the calcined ashes." It was used to describe compounds that had a basic pH and derived from ashes, such as potash.
Most atomic symbols are based on the latin name of the element. Latin was a common language of science for hundreds of years, and the symbols remained, though each language has their own name for the elements.