What does the number of neutrons in an atom give information about?

The number of neutrons in an atom directly contributes to the atomic mass of the element. Atomic mass is calculated by adding the number of protons and neutrons in the nucleus. Since protons and neutrons have nearly the same mass, the sum of these particles gives us the atomic mass unit (amu) of an atom. Variations in the number of neutrons result in different isotopes of an element, which have the same chemical properties but different masses due to the differing neutron count.

While the element type is determined by the number of protons (the atomic number), and the electron configuration depends on the number of protons and the arrangement of electrons, the charge of the atom is related to the balance between protons and electrons. Thus, neutrons specifically impact the atomic mass of the atom, making this the correct choice.