Question

Besides the central atom, what are the differences between \(\mathrm{CO}_{2}\) and \(\mathrm{SiO}_{2} ?\)

Short answer

The main differences between \(\mathrm{CO}_2\) and \(\mathrm{SiO}_2\) besides the central atom are: 1) \(\mathrm{CO}_2\) has double bonds while \(\mathrm{SiO}_2\) has single bonds, 2) \(\mathrm{CO}_2\) has a linear molecular shape, whereas \(\mathrm{SiO}_2\) forms a three-dimensional network, and 3) \(\mathrm{CO}_2\) is a gas with low melting and boiling points, while \(\mathrm{SiO}_2\) is a solid with high melting and boiling points.

Step-by-step solution

Examine the Central Atoms

Carbon (C) and Silicon (Si) are both elements found in group 14 of the periodic table. However, they have different properties due to their electron configurations and position in the carbon group. Carbon has the electron configuration 1s2 2s2 2p2, while Silicon has 1s2 2s2 2p6 3s2 3p2. Thus, Carbon and Silicon form different types of bonds with Oxygen.

Compare Bond Types

In carbon dioxide (\(\mathrm{CO}_2\)), the carbon forms two double bonds with the oxygen atoms, resulting in a linear molecular shape with a bond angle of 180°. The molecule has a molecular formula that shows these double bonds as O=C=O. On the contrary, in silicon dioxide (\(\mathrm{SiO}_2\)), the silicon atom forms single bonds with two oxygen atoms. Each oxygen atom also forms a single bond with another silicon atom, leading to an extended tetrahedral network of Si-O bonds.

Analyze Molecular Shape

In \(\mathrm{CO}_2\), the central carbon atom has no lone pair electrons and forms two double bonds with oxygen atoms, resulting in a linear molecular shape with a bond angle of 180°. Carbon dioxide is a discrete molecule. In \(\mathrm{SiO}_2\), the silicon atom tends to form tetrahedrally coordinated structures by forming single bonds with four oxygen atoms. In this case, the silicon atom sp3 hybridizes, leading to a tetrahedral geometry around the silicon atom. Silicon dioxide forms a continuous three-dimensional network of Si-O bonds, and is not a discrete molecule.

Compare Physical Properties

Carbon dioxide (\(\mathrm{CO}_2\)) is a gas at room temperature, and it is composed of discrete molecules. It has low melting and boiling points (-78.5 °C and -57.8 °C), and it cannot conduct electricity. Silicon dioxide (\(\mathrm{SiO}_2\)), on the other hand, exists as a solid at room temperature. It forms a covalent network of tetrahedrally coordinated Si-O bonds, which results in a high melting and boiling point (above 1600 °C) and low electrical conductivity. In summary, the differences between carbon dioxide and silicon dioxide, besides the central atom, are: 1. Bond types: \(\mathrm{CO}_2\) has double bonds while \(\mathrm{SiO}_2\) has single bonds. 2. Molecular shape: \(\mathrm{CO}_2\) is linear, while \(\mathrm{SiO}_2\) has a three-dimensional network. 3. Physical properties: \(\mathrm{CO}_2\) is a gas with low melting and boiling points, while \(\mathrm{SiO}_2\) is a solid with high melting and boiling points.

Key concepts

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. This is a crucial concept because it affects a molecule's properties and reactivity. The molecular geometry of

• Carbon Dioxide ( CO ₂): Carbon dioxide is linear due to the double bonds between carbon and each of the oxygen atoms. The bond angle is 180°, making it symmetrical. This straight-line structure affects how CO₂ interacts with other molecules and how it behaves as a gas.
• Silicon Dioxide ( SiO ₂): Unlike CO₂, silicon dioxide forms a more complex tetrahedral network. Silicon forms single bonds in an extended network, creating a structure much more solid at room temperature. This three-dimensional network provides SiO₂ with different physical properties compared to CO₂.

The unique geometries resulting from different bonding arrangements are key reasons why CO₂ is a gas, while SiO₂ is a solid under normal conditions.

Periodic Table Groups

Elements in the same group of the periodic table exhibit similar valence electron configurations, which influence their chemical behavior. Both carbon and silicon are in group 14, also known as the carbon group. They share certain characteristics such as having four valence electrons, enabling them to form four bonds, but there are essential differences.

• Carbon: Located in the second period, carbon's position leads to its ability to form multiple bond types, such as double and triple bonds, enhancing its versatility in chemical bonding.
• Silicon: As a third-period element, silicon cannot efficiently form multiple bonds with oxygen. Instead, it forms single bonds, leading to its robust three-dimensional network structure in compounds like SiO₂.

The differences in position in the group account for how these elements bond differently, influenced by their atomic structure and providing insight into their differing molecular geometries and properties.

Physical Properties

The physical properties of substances depend heavily on their molecular geometry and the types of bonds they contain. This dictates their state of matter at room temperature, melting and boiling points, and electrical conductivity.

• Carbon Dioxide ( CO ₂): As a result of its linear molecular structure, CO₂ is a gas with low boiling and melting points. It is not capable of conducting electricity because of its neutral, tightly bound molecules.
• Silicon Dioxide ( SiO ₂): Its extended tetrahedral network structure gives it the properties of a solid at room temperature. SiO₂ has a high melting point, unable to conduct electricity due to the nonmetallic nature of its robust network bonds.

Understanding these properties is vital in applications such as materials science and environmental science, where the behavior of gases and solids can dramatically influence processes and technology.