Final answer:
A neutral atom of aluminum-27 contains 13 protons, 13 electrons, and 14 neutrons; protons and electrons are always equal in a neutral atom, and neutrons are calculated by subtracting the atomic number from the isotope's mass number.
Step-by-step explanation:
A neutral atom of aluminum-27 contains 13 protons, 14 neutrons, and 13 electrons. The atomic number of aluminum (Al) is 13, which means it has 13 protons and, in a neutral atom, an equal number of electrons to balance the positive charge of the protons. The isotope aluminum-27 has a mass number of 27, which is the sum of protons and neutrons. To find the number of neutrons, we subtract the number of protons from the mass number: 27 - 13 = 14 neutrons.