$k_B = 1.380649 \cdot 10^{-23} (\frac{J}{K} = \frac{kg \cdot m^2}{K \cdot s^2}) =$ Boltzmann constant, from here.
$m = $ total mass of gas, in $kg$
$M = $ molar mass of gas, in $\frac{kg}{mol}$
$P = $ pressure, in $Pa = \frac{kg}{m \cdot s^2}$
$T = $ temperature, in $K$
$R = $ ideal gas constant
$V = \frac{m}{\rho} = $ volume, in $m^3$
$\rho = \frac{m}{V} = $ density, in $\frac{kg}{m^3}$
chemical amount: $n = \frac{m}{M}$, in $mol$
ideal gas law: $PV = nRT$ from here
$P = \frac{m}{M} RT = \rho \frac{R}{M} T$
$R_{spec} = \frac{R}{M}$
$P = \rho R_{spec} T$
Here is our relation of pressure, density, and temperature.

So how do we calculate $R_{spec}$?
$R_{spec} = \frac{k_B}{mass_{molecular}}$ from here. Is "molecular mass" the same as "molar mass"? No according to here. But this same page makes it sound like the two are about the same and often interchangeable, and provides no formula of equating them. No formulas at all. I guess whoever wrote this wasn't planning on using the concept in any equations.

molar mass: $mass_{molar} = mass_{relative} \cdot 0.99999999965(30) \cdot 10^{-3} \frac{kg}{mol}$ from here.
Relative atomic mass ... this is related to atomic mass but not equal to it? And atomic mass is circumstantial but relative atomic mass is constant ... and I can't find how the two relate. Kind of like "molar mass" vs "molecular mass". This is why I hate physics.
Standard atomic weight / relative atomic mass are used interchangeably.


$m_a =$ $\frac{g}{mol} =$ {{atomic_mass_in_kg_per_mol = atomic_mass_in_g_per_mol * 1e-3}} $\frac{kg}{mol} = $ atomic mass.
$n_v =$ nominal valency.
$\rho =$ $\frac{g}{cm^3} =$ {{material_density_in_kg_per_m3 = material_density_in_g_per_cm3 * 1e+3}} $\frac{kg}{m^3} = $ matter density.
$\rho_{res} = $ $\Omega \cdot m$ = electrical resistivity

TODO Graph lines of three axis of pressure, density, and temperature for each element.

Well, $\frac{P}{\rho} = R_{spec} T$. So it's just going to be a line with slope $R_{spec}$.