Final answer:
The mass number of an aluminum isotope with 13 protons and 14 neutrons is 27. It's identified as Al-27 on the periodic table based on its atomic number and mass number.
Step-by-step explanation:
The mass number of an isotope is calculated by adding the number of protons and neutrons together. In the case of the aluminum isotope with 13 protons, 13 electrons, and 14 neutrons, its mass number is the sum of the protons and neutrons, which equals 27 (13 protons + 14 neutrons = 27).
On the periodic table, aluminum is represented by the symbol Al and has an atomic number of 13, which is the number of protons in the nucleus. Since the number of protons determines the element, and this number doesn't change, you can identify the element as aluminum based on the atomic number alone. Given this information, we can confirm that the aluminum isotope described is Al-27.