How many neutrons does element X have if it's atomic number is 27 and it's mass number is 89?

element X has 62 neutrons The atomic number of an atom is the number of protons that atom has. And the mass number of an atom is the sum of the number of protons and neutrons an atom has. So to determine the number of neutrons, simply subtract the atomic number from the mass number. So 89 - 27 = 62 So element X has 62 neutrons.