Other atoms become ions much more readily—for example, all you have to do to make sodium ions is toss a hunk of sodium metal into water. Stand back! After the smoke clears, you’ll have a solution of sodium ions. Each of them is a sodium atom stripped of one of its electrons. Since the symbol for sodium is Na, we write: Na⁺¹. The point is, it’s still sodium, because the atomic number—the number of protons—hasn’t changed.