If sodium is a mineral then why does it react with the halide ions potassium bromide and potassium iodide?

Answer 1

Good question. The answer is found in the relative activity of one part of the chemical compound. In this case, the Periodic Table of elements and other information will show you that potassium (symbol K) is a much more active ion than sodium (symbol Na). In a "competition" as to which would get to combine with a halide ion (F, Cl, Br, I usually), the more active ion, K, would win the competition every time as compared to the Na ion.

Answer 2

Sodium is a metal, not a mineral. It reacts with potassium bromide and potassium iodide because it has a higher chemical reactivity than potassium and displaces it in the reaction to form sodium bromide and sodium iodide. This displacement reaction is a common phenomenon in chemistry.