In a neutral atom, how do the numbers of protons, neutrons, and electrons compare, and where are they located?

• A. Protons and electrons are in the nucleus; neutrons orbit the nucleus.
• B. Protons and neutrons are in the nucleus; electrons orbit the nucleus; in a neutral atom, the number of protons equals the number of electrons.
• C. Protons are in the nucleus; electrons, neutrons orbit the nucleus.
• D. All three particle types are in the nucleus.

Answer: (B)

The numbers of protons, neutrons, and electrons in an atom are arranged in two parts: a dense nucleus and a surrounding region where electrons are found. The nucleus houses protons (positive charge) and neutrons (no charge). The electrons (negative charge) occupy regions around the nucleus called orbitals or shells.

In a neutral atom, the total positive charge from the protons is exactly balanced by the total negative charge from the electrons, so the number of protons equals the number of electrons. Neutrons, while they contribute to the atom’s mass, don’t affect the electrical charge and can vary in number, leading to different isotopes of the same element.