A Level Physics Practice Exam

What is the major difference between protons and electrons?

1. Mass

2. Charge

3. Size

4. Location

The correct answer is: Charge

The major difference between protons and electrons lies in their charge. Protons carry a positive electrical charge, while electrons have a negative electrical charge. This fundamental property of charge is crucial in determining how these particles interact with each other and with other forms of matter. The difference in charge results in the attraction between protons and electrons, which is essential for the formation of atoms. Protons reside in the nucleus of an atom, while electrons exist in orbitals around the nucleus, maintaining an essential balance that defines the chemical properties of elements. While mass does differ between protons and electrons—with protons being significantly more massive—charge is the primary distinguishing characteristic. Size is not typically used to differentiate between these particles, as they do not have defined sizes in the same way that macroscopic objects do; rather, they are treated as point-like particles in many contexts. Location describes where these particles are found within the atom, but this characteristic follows from their properties rather than being a fundamental distinction.