How many grams are in 4.5 moles of lithium oxide?

Take the amu of Li which is 6.94 then multiply by two.=13.88 then grab the amu of O= 15.999 add these together and and you should get a number = 28.879

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.