Is Si a molecular, metallic, ionic, or covalent-network solid? Is a molecular, metallic, ionic, or covalent-network solid? Si is a molecular solid. Si is a metallic solid. Si is an ionic solid. Si is a covalent-network solid.

Silicon, Si forms covalent-network solids.

Explanation:

Silicon, Boron and Carbon are the elements that form covalent networks solids: solid materials whose units consists of chains or networks of atoms or molecules covalently bonded together. Silicon, Si has a similar structure to carbon, but not the exact hardness because Si-Si bonds are not as strong as carbon-carbon bonds.

An example of Si covalent compound is silicon dioxide.