Here's how to determine the positive and negative ions in NaCl (sodium chloride):

* Sodium (Na) readily loses one electron to achieve a stable electron configuration. When it loses an electron, it becomes a positive ion (Na+).

* Chlorine (Cl) readily gains one electron to achieve a stable electron configuration. When it gains an electron, it becomes a negative ion (Cl-).

Therefore, in NaCl:

* Na+ is the positive ion (cation)

* Cl- is the negative ion (anion)

This difference in charge is what creates the ionic bond that holds the compound together.