Question

Compare and contrast the structures of the following solids. a. diamond versus graphite b. silica versus silicates versus glass

Short answer

In summary, diamond and graphite both consist of carbon atoms but differ in structure, properties, and bonding, with diamond having a 3D tetrahedral lattice and graphite having planar sheets. Silica, silicates, and glass all involve silicon and oxygen, yet their structures and compositions vary. Silica has a 3D network of tetrahedral structures, silicates are minerals with various forms of silicate tetrahedra, and glass is an amorphous solid with a disordered atomic structure.

Step-by-step solution

a. Diamond and Graphite Structures

1. Diamond Structure: Diamond is composed of carbon atoms arranged in a tetrahedral lattice. Each carbon atom is covalently bonded to four other carbon atoms. This structure is 3D and is responsible for the hardness of diamond, making it one of the hardest known materials. 2. Graphite Structure: Graphite is made up of layers of carbon atoms arranged in a hexagonal lattice. In this arrangement, each carbon atom is covalently bonded to three other carbon atoms, forming planar sheets. The sheets are held together by weak van der Waals forces, allowing them to slide over one another easily. This gives graphite its lubricating properties and allows it to conduct electricity. 3. Comparison: - Both diamond and graphite contain carbon atoms - Diamond has a tetrahedral lattice with 3D covalent bonds, whereas graphite has a hexagonal lattice with planar sheets and weak van der Waals forces between them - Diamond is a good insulator, whereas graphite is a good conductor of electricity - Diamond is one of the hardest materials due to its covalent bonding, while graphite is a lubricant due to its loosely held layered structure

b. Silica, Silicates, and Glass Structures

1. Silica Structure: Silica, also known as silicon dioxide (SiO2), has a crystal lattice structure in which each silicon atom is bonded to four oxygen atoms, and each oxygen atom is bonded to two silicon atoms. This arrangement forms a 3D network of tetrahedral structures. 2. Silicates Structure: Silicates are minerals composed of silicon, oxygen, and one or more metallic elements. They are the most abundant minerals in Earth's crust. Silicates have a basic building block called the silicate tetrahedron (SiO4)^4-. These tetrahedra can connect to each other in various ways, forming different types of silicate structures, such as single, double, or sheet silicates. 3. Glass Structure: Glass is an amorphous solid, which means it does not have a long-range, regular crystal lattice structure. Instead, its atomic structure is more disordered. Glasses can be made from many different materials, but the most common type of glass is silica-based, meaning it is primarily composed of silicon and oxygen. In silica glass, the SiO2 tetrahedra are bonded to each other irregularly, which results in a non-crystalline and more breakable material than crystals. 4. Comparison: - Silica and silicates both contain silicon and oxygen, but silicates also contain one or more metallic elements - Silica is a crystal lattice of SiO2 with tetrahedral structures, while silicates are minerals composed of different forms of silicate tetrahedra (SiO4)^4- - Glass is an amorphous solid with a disordered atomic structure, typically made from silica but can also be made from other materials - Silica and silicates have more defined and organized structures compared to glass, which has a more random and disordered structure