Problem 12 - Chemistry: The Central Science in SI Units, Global Edition

Question

Silicon is the fundamental component of integrated circuits. Si has the same structure as diamond. (a) Is Si a molecular, metallic, ionic, or covalent- network solid? (b) Silicon readily reacts to form silicon dioxide, \(\mathrm{SiO}_{2,}\) which is quite hard and is insoluble in water. Is \(\mathrm{SiO}_{2}\) most likely a molecular, metallic, ionic, or covalent- network solid?

Step-by-Step Solution

Answer

(a) Si is a covalent-network solid. (b) SiO2 is a covalent-network solid.

Step 1: Determine the elements in Silicon (Si)

Silicon is a single element with the chemical symbol Si. It is in Group 14 of the periodic table, which means it has 4 valence electrons. The diamond-like structure of Silicon implies that it has a strong covalent bonding.

Step 2: Identify the type of bonding in Silicon (Si)

Silicon forms covalent bonds with other Silicon atoms due to its 4 valence electrons. These bonds result in a covalent-network structure, similar to that of diamond.

Step 3: Classify Silicon (Si) as a type of solid

Since Silicon has a covalent-network structure formed by covalent bonds, it is considered a covalent-network solid. So, answer (a) is that Si is a covalent-network solid. #Determine the classification of Silicon dioxide (SiO2) solid#

Step 4: Determine the elements in Silicon Dioxide (SiO2)

Silicon Dioxide consists of Silicon (Si) and Oxygen (O) elements. It has the chemical formula SiO2, which indicates that there is one Silicon atom and two Oxygen atoms in each molecule.

Step 5: Identify the type of bonding in Silicon Dioxide (SiO2)

Silicon and Oxygen both form covalent bonds to create a stable structure for SiO2. Each Silicon atom bonds with two Oxygen atoms in a tetrahedral arrangement, which results in a tightly bonded covalent-network structure.

Step 6: Classify Silicon Dioxide (SiO2) as a type of solid

Since Silicon Dioxide has a covalent-network structure formed by covalent bonds, it is considered a covalent-network solid. So, answer (b) is that SiO2 is a covalent-network solid.

Key Concepts

Silicon (Si)

Silicon is a fundamental element in modern technology, especially known for its use in integrated circuits and computer chips. It is represented by the symbol 'Si' on the periodic table. Being located in group 14, Silicon has four valence electrons. This is important because these electrons are involved in forming bonds with other elements or Silicon atoms themselves. The structure of Silicon is similar to that of diamond, favoring the formation of a robust framework consisting of numerous Silicon atoms bonded together. This strong network is held together by covalent bonds, making Silicon a covalent-network solid. Unlike other elemental forms, this special bonding structure makes it strong, with high melting and boiling points.

Silicon Dioxide (SiO2)

Silicon Dioxide, also commonly referred to as silica, is formed when Silicon reacts with Oxygen. The chemical formula for Silicon Dioxide is SiO2, consisting of one Silicon atom and two Oxygen atoms. In nature, Silicon Dioxide is found in various forms, including quartz.

• Silicon Dioxide forms through covalent bonding.
• A Silicon atom forms bonds with two Oxygen atoms in a tetrahedral structure.

This covalent-network solid is known for its strength and insolubility in water. Because of these properties, it is used in various applications, from glass making to electronic components.

Covalent Bonds

Covalent bonds are a type of strong chemical bond where atoms share pairs of electrons. This sharing allows each atom to attain the electron configuration of noble gases, achieving stability. Silicon, having four valence electrons, creates covalent bonds with other Silicon atoms or elements like Oxygen to form sturdy networks. These bonds are directional, meaning they hold specific orientations, contributing to the solid structures' stability.

• Covalent bonds are strong and are responsible for the high melting points of covalent-network solids.
• They usually form between non-metal elements.

In covalent-network solids like Silicon and Silicon Dioxide, these bonds create an expansive network that leads to unique properties such as hardness and electrical conductivity.

Periodic Table

The periodic table is an organized chart of elements, showcasing their atomic number, electron configuration, and recurring chemical properties. Each element occupies a unique position on the table, helping predict its behavior in chemical reactions. Silicon is found in group 14, which places it among elements like Carbon and Germanium, known as the Carbon group or tetrels. These elements uniquely share a tendency to form four covalent bonds due to their four valence electrons. The periodic table is crucial for identifying how elements will interact with one another.

• Elements in the same group have similar chemical and physical properties.
• The position of an element also indicates its valence electron number, which is essential in determining chemical bonding.

Understanding an element's placement helps in predicting the kind of bonding and compound structures it can form, as seen with Silicon forming covalent networks.

Valence Electrons

Valence electrons are the outermost electrons of an atom. They play a key role in chemical bonding and chemical reactions. These electrons are the ones involved in forming bonds with other atoms. Silicon, situated in group 14 of the periodic table, features four valence electrons, which are pivotal in forming covalent bonds.

• Having four valence electrons allows Silicon to form four bonds with other atoms.
• This results in a tetrahedral bonding structure when combining with Oxygen in Silicon Dioxide.

The number of valence electrons influences an element's chemical behavior, determining its reactivity and the types of compounds it forms. In the case of Silicon Dioxide, the Reactivity of Silicon with Oxygen, harnessed by these valence electrons, leads to the formation of a stable, rigid covalent-network solid.