State the three rules that define how electrons are arranged in atoms

The three correct rules or principles are the Aufbau Principle, Hund’s Rule, and the Pauli Exclusion Principle. Aufbau’s Principle states that each electron orbits the lowest energy orbital. It also states that all orbitals related to an energy level are of equal energy. Hund’s Rule states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals. And finally, the Pauli Exclusion Principle states that a maximum of two electrons may occupy a single orbital, but only if the electrons have opposite spins. Hope this helps.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.