What does it mean for two atoms to be isotonic?

The term "isotonic" is actually a bit misleading in the context of atomic structure. The correct term that pertains to atoms differing in neutrons while maintaining the same number of protons is "isotopes." Isotopes are variations of the same element that have the same number of protons (which defines the element) but differ in the number of neutrons, resulting in different atomic masses.

In this context, having the same number of neutrons would refer to isotopes of an element, where they both belong to the same atomic species but exhibit different mass numbers. The significance of isotopes lies in their different properties, such as stability and behavior in nuclear reactions. For example, Carbon-12 and Carbon-14 are isotopes of carbon, where Carbon-12 has six neutrons and Carbon-14 has eight.

The other options discuss characteristics like the number of protons, atomic mass, and electrons, which do not define isotopes. Protons identify the element rather than designate isotopes, atomic mass encompasses both protons and neutrons, and while having the same number of electrons relates to charge or ionization states, it does not pertain to the classification of isotopes. Thus, the concept of isotopes directly