What does atomic structure mean?

The definition of atomic structure is the positively charged nucleus and the negatively charged electrons circling around it, within an atom.

The definition of atomic structure is the positively charged nucleus and the negatively charged electrons circling around it, within an atom. An example of atomic structure is what gives energy to atoms and then to molecules.

1. o2(g)as a product

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.