# Interatomic spacing vs electric conductivity

I have a theory which may be wrong but I will write it down.If 2 elements at the same group (in solids)have the same crystal structure then the one with the biggest interatomic spacing has better electric conductivity.I don't know if anyone else has found this but I will give you 2 examples:

The crystal structure of diamond,silicon and germanium is face-centered cubic.We know that the order in conductivity of Ge>Si>Diam.

The order in interatomic spacing is Diam<Si<Ge.

Is this a coincidence or not?

• What about the next member of the series: $\alpha$ - tin? It is a semiconductor with the same structure as diamond, silicon and germanium. – Ed V Feb 20 at 13:04
• What group are you talking about? A family of chemical elements from the periodic table, a space group of a crystal or something else? – andselisk Feb 20 at 13:08
• If they have the same structure, then (generally speaking) the one with the biggest interatomic spacing is also the one with the greatest atomic number, and hence behaves more metal-like. So yes, it is no coincidence; it is a genuine relationship, albeit trivial. – Ivan Neretin Feb 20 at 13:32
• @andselisk same group of the periodic element – Clone Wars Feb 20 at 13:37