I know that the maximum number of electrons within a shell is equal to 2n^2. I would think that the noble gases would reflect this but that isn’t always the case
n = 1
2(1^2) = 2, this is the atomic number of He ✅
n = 2
2(2^2) = 8, plus the 2 e from n = 1, this is 10, which is the atomic number for Ne ✅
n = 3 2*(3^2) = 18, this is the atomic number for Ar, but I realized that the 3d orbital is empty. The 3rd energy level should have a total of 18 e and the total amount of electrons until the 3rd energy level should include 10 e from the previous 2. I understand that this is because of the aufbau principle, but it got me confused about how to consider noble gases. I thought they were supposed to have the maximum number of valence electrons, but then I thought what about group 12, Lutetium, and Lawrencium? Just based on their electron configuration, every orbital they have is completely occupied. I know these are very different from noble gases. I’m just wondering why, especially because these elements can be very reactive (right?).
Edit: I forgot to mention that after n = 3, nothing matches up at all.
n = 4
2(4^2) = 32, For Kr, Z = 36
n = 5
2(5^2) = 50, For Xe, Z = 54
n = 6
2(6^2) = 72, For Rn, Z = 86
And lastly, Idk if Oganesson is even considered a noble gas but it’s in the same group so I’ll put it here.
n = 7
2(7^2) = 98, For Og, Z = 118