# An isotope of iron has 28 neutrons. If the atomic mass of the isotope is 54, how many protons does it have?

Nov 1, 2016

The iron atom is characterized by an atomic number, "Z=26. That is every iron nucleus contains $26$ protons, 26, massive, positively charged, nuclear particles, by definition.
Of course, the nucleus also contains 28 neutrons, 28 neutral, massive nuclear particles, to give the ""^54Fe isotope, which is about 4% abundant, check on this.