Place the following elements in order from lowest number of protons to highest number of protons: S, Mg, N, Na, Se, Sr. Then give the following information about a neutral atom of each: name, atomic number, number of protons, number of electrons, group number.

Answer) by studying proton collisions hope this : )

Density and pressure

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.