Answer
a. $O^{2-}$
b. $K^+$
c. $Br^{-}$
d. $Sn^{4+}$
Work Step by Step
1. Identify each symbol using a periodic table:
a. 8 protons = O
b. 19 protons = K
c. 35 protons = Br
d. 50 protons = Sn
2. Calculate the charge of each ion.
charge = $nº protons$ - $nº e^-$
a. 8 - 10 = - 2
b. 19 - 18 = + 1
c. 35 - 36 = - 1
d. 50 - 46 = + 4
3. Write the charge in the upper right of the symbol. If it is equal to +1 or -1, you don't need to write the $1$. (Put the number before the $\pm$)
a. $O^{2-}$
b. $K^+$
c. $Br^{-}$
d. $Sn^{4+}$