Question

(a) Silicon is the fundamental component of integrated circuits. Si has the same structure as diamond. Is Si a molecular, metallic, ionic, or covalent- network solid? (b) Silica is \(\mathrm{SiO}_{2}\). What type of solid would you expect silica to form?

Short answer

(a) Silicon (Si) is a covalent-network solid due to its covalent bonding and three-dimensional network of atoms. (b) \(\mathrm{SiO}_{2}\) (Silica) can be classified as a covalent-network solid as well, due to its continuous network of covalently bonded Si and O atoms.

Step-by-step solution

(a) Analyzing Si properties and structure

The element Silicon (Si) belongs to Group 14 in the periodic table and has the same structure as diamond. It exhibits covalent bonding, which means that each Si atom shares electrons with four neighboring Si atoms.

(a) Classifying Si

Since Si has covalent bonding and forms a three-dimensional network due to its regular arrangement of atoms, it can be classified as a covalent-network solid.

(b) Analyzing \(\mathrm{SiO}_{2}\) properties and structure

Silica (\(\mathrm{SiO}_{2}\)) is a well-known compound and a principal component of glass. It consists of a silicon atom bonded to two oxygen atoms. Each oxygen atom, in turn, bonds to other silicon atoms, leading to a continuous network of \(\mathrm{Si}\) and \(\mathrm{O}\) atoms throughout the solid. The bonding between silicon and oxygen atoms in \(\mathrm{SiO}_{2}\) is predominantly covalent.

(b) Classifying \(\mathrm{SiO}_{2}\)

Since the bonding between Si and O atoms in \(\mathrm{SiO}_{2}\) is predominantly covalent and forms a continuous network, we can classify Silica (\(\mathrm{SiO}_{2}\)) as a covalent-network solid as well.

Key concepts

covalent-network solid

A covalent-network solid is a type of crystalline structure where a three-dimensional network of covalent bonds extends throughout the entire material. Unlike molecular solids, which are held together by intermolecular forces like hydrogen bonding or Van der Waals forces, covalent-network solids are bonded by covalent bonds. This contributes to their unique properties, such as high melting points, hardness, and electrical insulation in most cases.
Gemstones like diamond are excellent examples of covalent-network solids. In these structures, atoms are bonded in a continuous manner, making them very strong and stable. To break or melt a covalent-network solid, a large amount of energy is required to break all the covalent bonds simultaneously.
Covalent-network solids can often withstand high temperatures and pressures due to their robust bonding nature. This makes them valuable in industrial applications and in the production of durable goods.

silicon structure

Silicon, represented by the symbol Si, is a crucial element in the technology industry. This element is a member of the periodic table's Group 14 and shares a similar crystal structure to diamond.
Silicon atoms are tetrahedrally bonded to four other silicon atoms, forming a three-dimensional diamond cubic crystal structure. Each silicon-carbon bond involves sharing an electron pair, making them covalent bonds.
The strength of these covalent bonds is responsible for silicon's high melting point and semi-conductive properties, which are influential in its applications in electronics. Silicon’s structure allows electrons to move less freely compared to metals, which is why it behaves as a semiconductor rather than a good conductor.

silica properties

Silica, chemically known as \(SiO_{2}\), is commonly found in nature as quartz and is a principal component of sand. It forms when silicon (Si) atoms bond with oxygen (O) atoms in a complex three-dimensional array.
This arrangement characterizes silica as a covalent-network solid, where each silicon atom is surrounded by four oxygen atoms in a tetrahedral fashion. This covalent bonding provides silica with excellent material properties.
Silica’s structure is responsible for its notable properties, such as high thermal stability, chemical inertness, and hardness. It is insensitive to many acids and bases, adding to its utility in diverse applications such as glass making, ceramics, and semiconductor manufacturing.

covalent bonding

Covalent bonding is a chemical bond that involves the sharing of electron pairs between atoms. These bonds form strong connections, creating entities ranging from simple diatomic molecules to complex three-dimensional networks.
It is a fundamental type of bonding, especially predominant in non-metals and metalloids. During covalent bonding, atoms attain stability by filling their outer electrons shells. This creates strong internuclear forces that are particularly prominent in covalent-network solids like silicon and silica.
The formation of covalent bonds results in various structures with unique attributes across different compounds. For instance:

• Shared electrons accommodate bond strength and lengths.
• Structures ranging from simple molecules to extensive networks arise from covalent arrangements.

Understanding covalent bonding is essential for deciphering the structural and functional aspects of numerous materials.

periodic table group 14

Group 14 of the periodic table is also referred to as the carbon family, comprising carbon, silicon, germanium, tin, and lead. These elements exhibit a characteristic commonality in having four electrons in their outermost shell.
This paddling allows them to form covalent bonds, particularly four per atom, leading to a variety of structural forms including chains, sheets, and three-dimensional networks that are seen in covalent-network solids.
Silicon and carbon, for instance, often form tetrahedral structures that are foundational in both organic and inorganic chemistry. This ability to create extensive networks of covalent bonds underpins much of the diversity of compounds and materials derived from Group 14 elements.
The elements' semi-metallic to metallic properties evolve as you move down the group, influencing their electrical conductivity and other physical properties, crucial in applications ranging from semiconductors to soldering metal alloys.