What is the charge on lead with 78 electrons?

+4 On the Periodic Table, all elements are neutral. And that is the key to this problem.

Lead (Pb) on the periodic table has an atomic number of 82. Therefore it has 82 protons. How many electrons would it need to be a neutral atom then? Obviously, 82! So if we have 82 electors and 82 protons we have neutral lead, but we don't have 82 electrons we only have 78. Therefore neutral lead lost negatively charged electrons. When you lose a negative you become more positive.

So we have a charge of +4, since 82-78=4.

In general the solution to this problem is:

(Atomic Number) - (Number of Electrons) = (Net Charge)