A Level Physics Practice Exam

What is the role of protons in the atomic nucleus?

1. They are responsible for the atom's mass

2. They provide a negative charge

3. They give the nucleus a positive charge

4. They stabilize the neutron configuration

The correct answer is: They give the nucleus a positive charge

Protons play a crucial role in determining the characteristics of an atomic nucleus, with one of their primary functions being to contribute to the positive charge of the nucleus. This positive charge arises because protons are positively charged particles. Each proton carries a charge equal in magnitude but opposite in sign to that of an electron, which means that the presence of protons in the nucleus attracts the negatively charged electrons that orbit around it. This interaction is fundamental to the overall stability and structure of the atom. Additionally, the number of protons in the nucleus, known as the atomic number, determines the element's identity. An increase in the number of protons leads to a greater positive charge in the nucleus, which can affect the electron configuration and chemical properties of the element. Furthermore, while protons contribute to the mass of the atom (along with neutrons), they do not stabilize the neutron configuration directly. Neutrons do provide stability to the nucleus, but this is largely due to the balance of forces between protons and neutrons rather than a direct interaction based solely on protons.