What is the nuclear charge of an iron atom?

The net charge is the difference between the number of protons, which have positive charges, and electrons, which have negative charges. All atoms and ions of iron have 26 protons. Iron's atomic number is 26. Atoms don't gain or lose protons.

The nuclear charge is the total charge of all the protons in the nucleus. It has the same value as the atomic number. The nuclear charge increases you go across the periodic table.