The force that holds electrons in orbitals around the nucleus of an atom is called the electromagnetic force. It arises due to the attraction between the negatively charged electrons and the positively charged protons in the nucleus. The electromagnetic force is one of the four fundamental forces of nature and is responsible for a wide range of phenomena, including the interactions between charged particles.
The strength of the electromagnetic force is typically quantified by the fine-structure constant, denoted by α (alpha), which has a value of approximately 1/137. This constant is a dimensionless quantity and represents the strength of the electromagnetic interaction relative to other fundamental forces.
In comparison to the electromagnetic force, the strong nuclear force is the force responsible for binding protons and neutrons together in the nucleus. It is significantly stronger than the electromagnetic force at very short distances (within the nucleus). However, the electromagnetic force dominates the interactions between the electrons and the nucleus because the electrons are located outside the nucleus in the electron cloud.
It's important to note that the behavior of electrons in atoms is described by quantum mechanics, which introduces additional complexities and mathematical formalism to accurately describe the electron's behavior in orbitals. Quantum mechanics provides a probabilistic description of electron positions and their interactions with the nucleus based on wave functions and energy levels.