What holds atoms together?

• A. the gravitational pull between the nucleus and the electrons.
• B. the strong nuclear force between protons and neutrons.
• C. the electrostatic force of attraction between the protons in the nucleus and the surrounding electrons.
• D. the magnetic attraction between electrons and neutrons.

Answer: (C)

Electromagnetic forces hold atoms together. The negatively charged electrons are attracted to the positively charged protons in the nucleus by the electrostatic (Coulomb) force. This attraction creates the stable electron cloud that surrounds the nucleus and keeps the atom bound as a whole. The strong nuclear force is what binds protons and neutrons inside the nucleus itself, not the entire atom, and gravitational forces are far too weak to matter at atomic scales. Neutrons have no net charge, so magnetic attraction isn’t what binds electrons to the nucleus. Therefore, the binding force between protons in the nucleus and the surrounding electrons—the electrostatic attraction—is the correct description.