Hi Joel,
I read your essay with interest, although I have no applicable education or experience. I had to search a bit before finding what spdf refers to in Wikipedia. Unfortunately, I'm really not able to assess your essay regarding the periodic table.
However, by investigating, I did happen upon you Gravity page. I also had difficulty comprehending your proposal for gravitation, but it did seem more substantive that some other proposals for a electromagnetic basis for gravitation. While I do suspect that electrostatic interactions may be responsible for some proximal effects (I suspect that GR's proximity compensation for Mercury's orbit is merely a fudge factor), I doubt that they play a significant role in gravitation's fundamental effects.
On your Gravity page, there's a footnote that asks two questions:
1. "Does a hydrogen star have the same gravitational constant as a neutron star with the same mass?"
2. "Closer to home, does the sun have precisely the same gravitational constant as the earth?"
I find these quite interesting, since I'd been asking others to explain, if gravitation is an EM effect, how a gravitational constant works equally well for the cold Moon as the hot Sun.
As I understand, while luminosity is most often used to estimate the mass of main-sequence stars, I think that mass estimates for non-luminous objects such as planets and even Neutron stars are often derived from their apparent gravitational effects. In this case, it seems there may be no way to independently validate the gravitational constant's veracity in representing non-luminous masses' gravitational effects.
If the total mass can be precisely independently determined for the Earth-Moon system and for the Sun-Earth, it would seem that using a single gravitational constant for both system's orbits would yield incorrect results for one or both systems.
In this regard, you might find my brief essay somewhat interesting: Inappropriate Application of Kepler's Empirical Laws of Planetary Motion to Spiral Galaxies Created the Perceived Galaxy Rotation Problem - Thereby Establishing a Galactic Presence for the Elusive, Inferred Dark Matter.
Thanks for your essay - intriguing work!