The atomic number of an element represents the number of protons in the nucleus of an atom. In the case of aluminum (Al), the atomic number is 13, indicating that it has 13 protons.
However, the number of protons alone does not determine the mass of an atom. The mass of an atom is determined by the combined mass of its protons and neutrons, which are collectively known as nucleons.
To find the mass of an aluminum atom, we need to consider the number of neutrons it has. The atomic mass of aluminum is approximately 26.98 atomic mass units (amu). This value represents the weighted average mass of all naturally occurring isotopes of aluminum, taking into account their relative abundances.
To determine the number of neutrons in an aluminum atom, subtract the atomic number (number of protons) from the atomic mass:
Number of neutrons = Atomic mass - Atomic number Number of neutrons = 26.98 amu - 13 Number of neutrons = 13.98 amu
Therefore, an aluminum atom has approximately 14 neutrons. The mass of an aluminum atom is determined by the combined mass of its protons and neutrons, which in this case is approximately 27 atomic mass units (amu).