Instead of 3 chloride ions, our drawing will have 1 chloride ion around the central magnesium ion.
We reduce the number of chloride ions. Since the concentration of MgCl₂ is half (0.05 M compared to 0.10 M in the original drawing), we now draw half the number of chloride ions surrounding the magnesium ion.
We also maintain the magnesium ion. The concentration of magnesium ions remains the same (0.05 M) regardless of the change in chloride ion concentration. Therefore, your drawing should still have 1 central magnesium ion.
We make sure to keep the spacing consistent and maintain the same approximate distance between the ions in your drawing as in the original image. This helps represent the relative positions of the particles in the solution.