Carbon atomic number 12
The bottom number of the atom is the atomic number which is based on the number of protons. The 14 is the total mass of the atom. Carbon 14 has 6 protons and 8 neutrons for a total mass of 14Atoms of both isotopes of carbon contain 6 protons. Atoms of carbon12 have 6 neutrons, while atoms of carbon14 contain 8 neutrons. A neutral atom would have the same number of protons and electrons, so a neutral atom of carbon12 or carbon14 would have 6 electrons. carbon atomic number 12
The atomic number is the number of protons in the nucleus of an atomic, hence no matter the isotope, the atomic number remains the same but that can't be said for the mass number as it depends on the number of neutrons as well.