What is the primary force that holds electrons in orbit around the nucleus?

The primary force that holds electrons in orbit around the nucleus is the electromagnetic force. This force is a fundamental interaction that occurs between electrically charged particles. In the context of an atom, the negatively charged electrons are attracted to the positively charged protons located in the nucleus due to this electromagnetic force. This attraction is what keeps the electrons in their respective energy levels or orbitals around the nucleus.

Other forces mentioned, such as gravitational force, are significantly weaker at the atomic scale and have little relevance in the behavior of subatomic particles. Centrifugal force is a perceived force that arises when an object moves in a circular path and does not play a role in the atomic structure. Nuclear force is a strong force that operates at the level of protons and neutrons within the nucleus, but it does not influence the interaction between electrons and the nucleus directly. Therefore, in the atomic model, it is the electromagnetic force that effectively governs the stability and arrangement of electrons around the nucleus.