ACS Chemistry Practice Exam 2025 – The All-in-One Guide to Exam Success!

Protons carry a positive charge, which fundamentally defines their role in atomic structure. Each proton has a charge of +1 elementary charge, contributing to the overall charge of the nucleus of an atom. This positive charge is crucial because it attracts negatively charged electrons, helping to hold them in orbit around the nucleus and thus maintaining the stability of the atom.

In the context of an atom, the presence of protons (and their positive charge) also influences the overall electrical characteristics of the element as well as its chemical behavior. The number of protons in an atom's nucleus is what determines its atomic number and, consequently, its identity as a particular element.

The options representing neutral or negative charges are not applicable to protons, as they do not have the characteristics associated with those types of charges. Additionally, the notion of variable charge does not apply to protons, as they consistently carry a positive charge irrespective of the context.