Sodium is represented by the symbol Na because it comes from the Latin word natrium.

Here's a breakdown:

* Latin: The ancient Romans knew about sodium, even though they couldn't isolate it as a pure element. They called it "natrium", which referred to a compound found in soda ash (sodium carbonate).

* Symbol: When scientists started developing a system for naming chemical elements, they often used Latin names as the basis for symbols. So, Na became the abbreviation for sodium.

It's interesting to note that many other elements also have symbols derived from Latin, such as potassium (K from "kalium") and gold (Au from "aurum").