What are the properties of the unidentified elements, Θ Ω Σ and Δ?

Solution 1:

A Fission laser produces these results when fed the extra atoms in the ResearchNet sandbox mode.

Θ → Fm 100 x2
Ω → Md 101 + Fm 100
Σ → Md 101 x2
Δ → Md 101 + No 102

This implies that the elements have the following atomic numbers:

Θ - 200
Ω - 201
Σ - 202
Δ - 203

Although I have not tested it, I imagine that fusing them would be like trying to fuse any other combination that does not produce a valid element, nothing happens. Also note that attempting to fuse Fm and Fm together into Θ does not work. The same is likely the case for the others.

A quick experiment in the puzzle generator reveals that they can accept twelve bonds, which is three in each direction, the maximum possible number.

I tested all this using the ResearchNet user generated puzzle system, which allows much greater flexibility in setting up testing scenarios.