Solid carbon dioxide exists as discrete molecules held together by weak intermolecular forces. How does solid silicon dioxide differ structurally?

1. Carbon and silicon are in the same periodic group, but they behave very differently when bonded to oxygen. 2. The text contrasts them directly: "silicon dioxide is a covalent network solid. In silicon dioxide, each silicon atom links to four oxygen atoms by single bonds directed toward the corners of a regular tetrahedron." 3. This continuous three-dimensional network of Si-O single bonds (unlike CO2's small double-bonded molecules) is why quartz is a hard solid while dry ice sublimes easily. 4. Silicon dioxide is neither a molecular solid like CO2, nor an ionic compound, nor a metal -- it is a covalent network solid. 5. So the key structural difference is that SiO2 forms one giant covalent network, not separate small molecules. _Source: OpenStax Chemistry Ch 18 "Representative Metals, Metalloids, and Nonmetals", p.984 §18.3 Structure and General Properties of the Metalloids_