Question

Silicon carbide $\mathbf{\left(}\mathit{S}\mathit{i}\mathit{C}\mathbf{\right)}$is an extremely hard substance. Propose a structure for $\mathbf{\left(}\mathit{S}\mathit{i}\mathit{C}\mathbf{\right)}$.

Short answer

The structure of $SiC$is diamond.

Step-by-step solution

Description of hexagonal crystal structure

Two of the angles in a hexagonal crystal structure are perpendicular,while the other is ${\mathbf{120}}^{\mathbf{°}}$. The two sides enclosing the ${\mathbf{120}}^{\mathbf{°}}$ angle must be equal (a = b) for this to happen, whereas the third side (c) is at 90° to the other sides and can be any length.

The structure of  SiC

• When carbon is heated with $Si{O}_2$, $CO$is produced, and silicon carbide, $SiC$, is formed.
• Carborundum is a highly hard substance that is commonly used as an abrasive.
• Moissanite is one of the silicon carbide crystalline polymorphs.
• This is a naturally occurring silicon carbide that is similar to a diamond in terms of its high hardness.
• This silicon carbide has a hexagonal crystal structure.
• Similar to diamond, the crystalline structure is maintained together by strong covalent bonds.

Thus, similar to diamond, it has a strong covalent bond.