Question

How would you convert silica into a glassy substance? Explain the structure of the substance thus obtained.

Answer 1

1. Silica (SiO₂) is converted into a glassy substance (glass) by heating it to a high temperature until it melts and then rapidly cooling the molten mass.
2. This rapid cooling prevents the atoms from arranging into a regular crystalline structure, resulting in an amorphous solid.
3. The substance obtained is amorphous silica, commonly known as glass.
4. It consists of SiO₄ tetrahedra that are randomly arranged and not periodically ordered like in crystalline quartz.
5. Unlike crystalline quartz, in glassy silica, the Si–O–Si bond angles and bond lengths vary, creating a disordered, amorphous structure.
6. This lack of regular pattern is what makes it a glassy (amorphous) solid.
7. The glass has short-range order (the local arrangement of atoms is regular) but no long-range order, which is why it lacks a sharp melting point and is transparent.