To determine the charge on the ion, we need to calculate the difference between the number of protons and electrons.

Given atomic number = 16 (represents the number of protons)

Number of electrons = 18

Mass number = 33 (sum of protons and neutrons)

The mass number can be expressed as:

Mass number = Number of protons + Number of neutrons

By rearranging the formula:

Number of neutrons = Mass number - Number of protons

Number of neutrons = 33 - 16 = 17

Now, let's calculate the charge on the ion:

Ion's Charge = Number of protons - Number of electrons

Ion's Charge = 16 - 18

Ion's Charge = -2

The ion has a charge of -2, indicating that it has gained two extra electrons compared to the number of protons. This results in a net negative charge.