Question

Write the correct ionic formula when given two elements that bond ionically.

Answer 1

A + H20 -> [A+][OH-] + [H+]
B + H20 -> [H+][B-] + [OH-]
A + B + 2H20 -> [A+][B-] + 2H20
A + B + 2H20 - 2H20 -> [A+][B-]
A + B -> [A+][B-]

despite i have placed [A+][OH-] and [H+][B-], those bonds are not ionic.
only [A+][B-] is. only because these 2 elements have the requisites to form it.

However, the simple answer is
A + B -> [A]^+n [B]^-n
in my example n=1.