Valance band to Conduction Band (Valance Electron), Energy Band Gap Levels

GoldenAtlantis

I am looking to calculate the energy gap of for starters periodic elements and were wondering how we could get the list and calculation. Is there a table somewhere based on certain temperatures and constants of energy gap level? We would like to get a list of the energy gap energy for valance electrons. This would be for crossing from valance band through the energy band gap to the conduction band. We were wondering if this is calculated or experimentally determined (With photon, heat, spectrometer, etc). So that we could extrapolate out to other elements; if we had these constants how could we get the energy level?

Example:
Material: Solid, Element: Tin (Sn), Valance electrons: 4, Temp: 300K, Pressure: Ambient, Quantity of atoms: 1 atom, Velocity: Not sure, Density: at moment one atom, Not sure if this has effect (Fermi), Fermi Energy: 12.2 eV, Fermi Temp: 11.8x10^4K, Fermi Velocity: 1.9x10^6 m/s, Free electron density: 14.8 N/Vx10^28/m^3

What elements of above or missed data would be needed to calculate energy gap level at various temps/pressure? Or is the gap not calculated and experimentally determined (If so is there a table at some constants), if so any table/source for elements and compounds would be helpful.

Tried these but you need the wave length or frequency which would mean table. E=hc/λ, E=hf

Thanks, any sources to review or read would be great.