Question

Which of the following properties correctly explain \(\mathrm{SiO}_{2} ?\) (a) Linear, basic (b) Tetrahedral, acidic (c) Tetrahedral, basic (d) Linear, acidic

Short answer

The correct properties that explain \texorpdfstring{\(\mathrm{SiO}_{2}\)}{SiO2} are tetrahedral geometry and acidic behavior, which is option (b).

Step-by-step solution

Understand the Chemical Structure of \texorpdfstring{\(\mathrm{SiO}_{2}\)}{SiO2}

Silicon dioxide, \texorpdfstring{\(\mathrm{SiO}_{2}\)}{SiO2}, is known to have a three-dimensional network where each silicon atom is covalently bonded to four oxygen atoms. This arrangement around a central silicon atom is known as a tetrahedral geometry.

Determine the Molecular Geometry

From step 1, we know that silicon dioxide has a tetrahedral geometry. This eliminates options (a) and (d) since they describe linear geometries.

Assess the Acid-Base Behaviour

Silicon dioxide is a covalent network solid and is known for its acidity, especially when it reacts with strong bases to form silicate salts. Consequently, it does not act as a base. This eliminates option (c) as it incorrectly identifies \texorpdfstring{\(\mathrm{SiO}_{2}\)}{SiO2} as basic.

Conclude with the Correct Option

After assessing the structure and acid-base behavior of \texorpdfstring{\(\mathrm{SiO}_{2}\)}{SiO2}, it is clear that the correct option is (b) Tetrahedral, acidic.

Key concepts

Tetrahedral Molecular Geometry

When visualizing the structure of molecules in chemistry, the tetrahedral molecular geometry emerges as a significant and common shape. It consists of a central atom surrounded symmetrically by four atoms at the corners of an imaginary tetrahedron. Think of it like a pyramid with a triangular base. This spatial arrangement is fundamental because it minimizes electron repulsion, allowing the atoms to maintain stable bonds.

In the case of silicon dioxide, SiO₂, the central silicon atom forms bonds at a roughly 109.5-degree angle with four surrounding oxygen atoms. This creates the noted tetrahedral shape, which is not just theoretical but also critical to the material's properties. It's this geometric form that gives SiO₂ its strong structural integrity, making it prevalent in materials like quartz and sand.

Chemical Structure of SiO2

Silicon dioxide, or SiO₂, exhibits a fascinating and complex chemical structure, which is pivotal in understanding its properties and applications. Each silicon (Si) atom in SiO₂ is linked covalently to four oxygen (O) atoms, forming a continuous network of silicon-oxygen tetrahedra. This configuration weaves a robust, three-dimensional lattice that spans throughout the material.

Due to its extensive network, SiO₂ is classified as a covalent network solid, attributing to its high melting and boiling points. It’s also why materials like glass and some types of rocks are so hard and durable. In addition, the high bond strength between the silicon and oxygen atoms explains why SiO₂ doesn’t conduct electricity well - the electrons are tightly held within the bonds and are not free to move about.

Acid-Base Behaviour in Chemistry

In chemistry, understanding the acid-base behavior of substances is key to predicting reactions and interactions. Acids are substances that can donate a proton (H⁺), while bases are those that can accept a proton. However, the acid-base behavior of SiO₂ is quite specific due to its strong covalent structure.

Despite not having any hydrogen atoms, SiO₂ exhibits acidic properties; it is considered a Lewis acid because it can accept electron pairs. When SiO₂ reacts with a strong base, it can form silicate salts, indicative of its acidic nature. This counterintuitive behavior is a striking example of how acid-base concepts in chemistry extend beyond the traditional definitions involving hydrogen. Understanding this peculiar acid-base chemistry is crucial for students tackling the intricate world of inorganic chemistry.