[p1necone]

Are you referring to it being a solid? Silicon dioxide would be a gas at some temperature - likewise CO2 is solid below -78.5c. Extraterrestrial life doesn't have to be anywhere near the same temperatures as us.

Also I don't see why you couldn't have an organism that "breathes" solid material.

[m1el]

I researched this topic for a while, and I came to conclusion that Si-based life is nearly impossible for several reasons.

> Silicon dioxide melting point: 1710 °C

No complex chemistry can survive these temperatures. SiO2 is only soluble in HCl and HF, which are very reactive, so no solubility either.

> Also I don't see why you couldn't have an organism that "breathes" solid material.

All of known biological chemistry relies on some sort of solubility for reagents. I don't think there's any known organism that can get rid of solid waste from the entire volume of the organism.

[ars]

You could react silicon with fluoride instead of oxygen. Silicon tetrafluoride melts at −90 °C (and boils at -86).

You can also have chlorine as your oxidizer and make Silicon tetrachloride which melts at −68.74 °C and boils at 57.65 °C, that temperature range is perfect.

What else will change by having a chlorine instead of oxygen atmosphere?