Why is sio2 solid and co2 gas?

Chemistry Made Simple Here’s the deal: CO2 is a gas because it’s a small, linear molecule with weak intermolecular forces (London dispersion forces), so it floats around at room temp. SiO2, though, is a solid because it forms a giant, covalent network—like a 3D lattice of silicon and oxygen atoms bonded tightly, think sand or quartz. It’s why glass (mostly SiO2) is rock-hard but CO2 fizzes out of your soda. Molecular structure is everything! Careers360 explains it well. Cool, right?