A carbon-12 atom has 6 protons, 6 neutrons, and 6 electrons. How many protons does a carbon-14 atom have?
carbon-12 and carbon-14 are isotopes of the same element, carbon.
this means that they have the same number of protons and the same number of electrons - just different numbers of neutrons
the numbers 12 and 14 show the mass number of each isotope: the number of protons added to the number of neutrons.
meanwhile, the atomic number of an element is the number of protons, or the number of electrons, it has (since, in a stable atom, the number of protons and electrons are the same).
all isotopes of carbon atoms have
a carbon-12 atom has
a carbon-14 atom has