• 2.24: Write the symbol for an isotope • that contains 92 protons and 146 neutrons • 2.30: Which are true? • An atom with an atomic number of 7 and a mass number of 14 is identical to an atom with an atomic number of 6 and a mass number of 14. • Neutral atoms have the same number of electrons as protons. • The mass of an atom is due to the sum of the no. of protons, neutrons and electrons.