Question

According to which process, sublevels and orbitals are filled with electrons in order of increasing energy?

Answer 1

aufbau

According to the Aufbau process, sublevels and orbitals are filled with electrons in order of increasing energy. Since the s sublevel consists of just one orbital, the second electron simply pairs up with the first electron as in helium. The next element is lithium and necessitates the use of the next available sublevel, the 2 s .