Answer
a. $Ni^{2+}$: 28 protons and 26 electrons;
b. $Se^{2-}$: 34 protons and 36 eletctrons;
c. $Fe^{3+}$: 26 protons and 23 electrons.
Work Step by Step
1. Determine the number of protons, by looking at the atomic number of that element on a periodic table.
a. Ni: 28 protons.
b. Se: 34 protons.
c. Fe: 26 protons.
2. Calculate the amount of electrons:
Number of electrons = Number of protons - Charge
a. 28 - (+2) = 26 electrons.
b. 34 - (-2) = 36 electrons.
c. 26 - (+3) = 23 electrons.
