Answer:
The number of energy levels filled in an atom is determined by the number of orbitals.
Step-by-step explanation:
The highest numbers of the electrons in a given energy level relies on the presence of number of orbitals. In one orbital it contains two electrons. Electron that are present in the outer energy level of atom are known as the valence electrons. Which remains as the determining factor of the reactivity of the element. Lights are being emitted when an electron comes from higher state to the lower state.