Now there are exceptions to Hund's Rule for that is why it is a rule and not a law of physics.
The exceptions start with chromium at 4s1, 3d5 and then copper at 4s1, 3d10.
Now what I have started to do in explaining Hund's Rule by deriving it from the Maxwell Equations, is that the rule is an interplay between electrons as matter transverse waves and electrons as longitudinal wave. Electrons as matter transverse waves want to be single and unpaired and form parallel attraction of the Ampere law. However, this condition of being single and unpaired and attractive force runs out in a higher subshell of orbits, as the second electron in an orbital with a longitudinal wave is less energy than the new higher subshell.
So how do we picture a up electron with a paired down electron in a suborbital? In Old Physics we just used words of paired, and "up and down", and spin but we never really gave rhyme nor reason to any of these words as a mechanism of the Maxwell Equations.
This is where New Physics comes in with the Maxwell Equations as axioms and ultimate explanation. So we have an up and down electron and what we do is replace up with a electron as matter transverse wave and we replace down electron as a electron of longitudinal wave. And for paired suborbital electrons such as 4s2 in zinc we picture that as
E- 2M+ 2M- E-
which is a combination of the matter transverse wave
E- M+ M-
and the longitudinal wave
E- M+ M-
An electron as a matter transverse wave requires less energy than an electron that is a longitudinal wave. And one way to picture this is the E- the electric field is predominant for the matter transverse wave, whereas in the longitudinal electron the M+ and M- are predominant.
Now they pair in a suborbital because they follow the Ampere Law of parallel attract so that if the two electrons were matter transverse waves, they would repel and not form the suborbital pairing. So that for zinc 4s2, 3d10 as the last electron to enter zinc it was a matter transverse wave electron, but switches over into a longitudinal wave electron to fit into that last suborbital pairing up with the other electron.
Now in astronomy, since the Maxwell Equations are the same axioms over all of astronomy we have a similarity of how stars, planets and their moons come into existence and how they orbit. Now we do not have a Nebular Dust Cloud origin of the Solar System but rather a Dirac new radioactivities of constant accretion of new particles that gives birth to the Sun and solar system and slowly grows them. And in that process, we should see something similar to a Hund's Rule. So if we imagine the planets as electrons, their orbits should follow some mathematical rule and we see it in the Titius Bode Rule, but we want something similar to the Hund's rule of filling up orbits and whether planets share the same orbits.
We do not see any orbits with two planets in them, however we do see planets with many moons. Jupiter has 67 moons and Saturn approximately 62 moons. So as the Solar System was built from Dirac New Radioactivities particles over 9-8 billion years ago, many of those new particles went into building moons around existing planets rather than a newer planet beyond Pluto or the Kuiper belt.
Now the orbit of the Asteroids was likely a orbit that had two planets in it, two the size of present day Pluto perhaps (have to check on their relative masses), and that perhaps they existed for 4 billion years in a orbit of two planets when one caught up with the other and collided and broke apart into our present day Asteroid belt.
-- Approximately 90 percent of AP's posts are missing in the Google newsgroups author search starting May 2012. They call it indexing; I call it censor discrimination. Whatever the case, what is needed now is for science newsgroups like sci.physics, sci.chem, sci.bio, sci.geo.geology, sci.med, sci.paleontology, sci.astro, sci.physics.electromag to?be hosted by a University the same as what Drexel?University hosts sci.math as the Math Forum. Science needs to be in education?not in the hands of corporations chasing after the next dollar bill.?Besides, Drexel's Math Forum can demand no fake names, and only 5 posts per day, of all posters which reduces or eliminates most spam and hate-spew, search-engine-bombing, and front- page-hogging. Drexel has?done a excellent, simple and fair author- archiving of AP sci.math posts since May 2012?as seen?here: