The easiest way to determine the type of bonding that occurs between sodium and chlorine is to find the difference of their electronegativities.
Sodium has an electronegativity of 0.93 and chlorine an electronegativity of 3.16:
The difference of electronegativities is 2.23, which is greater than 1.7. It means that they form a ionic bond.
The resulting compound is what we know as table salt, which is NaCl, sodium chloride.
We expect that this compound is soluble in water.