Describe the structure and bonding in silicon dioxide.

Silicon dioxide, also known as silica, has a giant covalent structure with each silicon atom bonded to four oxygen atoms.

Silicon dioxide, or silica, is a compound that consists of silicon and oxygen atoms. It is a prime example of a substance with a giant covalent structure. This means that it is made up of a large number of atoms, all of which are connected by covalent bonds. These bonds are formed when two atoms share a pair of electrons, resulting in a strong bond that is difficult to break.

In the case of silicon dioxide, each silicon atom is bonded to four oxygen atoms. This forms a tetrahedral arrangement, with the silicon atom at the centre and the oxygen atoms at the corners of a tetrahedron. This pattern repeats throughout the entire structure, creating a three-dimensional network of atoms. This arrangement is very stable and results in a high melting and boiling point for silicon dioxide, as a lot of energy is required to break the strong covalent bonds.

The bonding in silicon dioxide is purely covalent, meaning that there are no free electrons or ions. This results in silicon dioxide being a poor conductor of electricity, as there are no charged particles available to carry an electric current. It is also insoluble in water and most other solvents, due to the strong covalent bonds within its structure. To understand more about the formation and properties of covalent bonds, see Formation of Covalent Bonds.

IB Chemistry Tutor Summary: Silicon dioxide, or silica, is made up of silicon and oxygen atoms in a large covalent structure, where each silicon is connected to four oxygens. This arrangement forms a stable, 3D network with high melting and boiling points, making it a poor conductor of electricity and insoluble in water. Its structure is based on shared electrons between atoms, creating strong bonds. For additional details on how these structures are organised on a larger scale, refer to Lattice Structure.