Question

Silica is a network solid of silicon and oxygen atoms. The empirical formula for silica is \(\mathrm{SiO}_2\), In silica, to how many oxygen atoms is each silicon bonded? A. 1 B. 2 C. 3 D. 4

Short answer

D. 4

Step-by-step solution

Understand the Empirical Formula

The empirical formula for silica is \(\text{SiO}_2\). This means for every silicon atom, there are two oxygen atoms.

Bonding in Network Solids

In a network solid like silica, each silicon atom forms bonds with multiple oxygen atoms. The structure is similar to that of quartz where each silicon atom is connected to oxygen atoms in a tetrahedral pattern.

Count the Bonds

In the structure of silica, each silicon atom is bonded to four oxygen atoms. These bonds form a three-dimensional lattice structure common to many network solids.

Compare with Answer Choices

Given the bonding structure, each silicon atom is bonded to 4 oxygen atoms, which corresponds to option D.

Key concepts

Empirical Formula

The empirical formula of a compound provides the simplest whole-number ratio of the atoms of different elements in that compound. For silica, the empirical formula is \(\mathrm{SiO}_2\).
This indicates that for every silicon (Si) atom, there are two oxygen (O) atoms in the network.
It's important to note that the empirical formula does not give information about the exact number of atoms in a molecule, but rather the ratio between them.
Understanding the empirical formula helps in determining how different atoms are bonded in a compound, especially in network solids like silica.

Network Solid

A network solid is a type of chemical compound where the atoms are connected in a continuous network extending throughout the material.
In these solids, atoms are covalently bonded to one another, forming an extensive three-dimensional structure.
Silica (\(\mathrm{SiO}_2)\) is a perfect example of a network solid. Here, silicon and oxygen atoms form a vast network.
Each silicon atom in silica is bonded to multiple oxygen atoms, creating a sturdy and stable structure.
This type of bonding and structure significantly contributes to the hardness, high melting points, and other physical properties of network solids.

Tetrahedral Structure

In silica, silicon bonds with oxygen atoms in a tetrahedral arrangement. This means each silicon atom is at the center of a tetrahedron, bonded to four oxygen atoms at the corners.
This geometric pattern helps in creating a balanced and stable structure.
Tetrahedral structures are common in many network solids because they efficiently fill space and provide stability to the structure.
Understanding the tetrahedral bonding pattern is crucial as it explains why each silicon atom in silica is bonded to exactly four oxygen atoms.

Three-Dimensional Lattice

Network solids like silica form a three-dimensional lattice structure. This is a repeating pattern that extends in all directions, creating a large and stable solid.
In such a lattice, each silicon atom is surrounded by four oxygen atoms, forming a tetrahedral unit.
These tetrahedrons are interconnected, with each oxygen atom being shared by two silicon atoms, contributing to the extensive and robust nature of the lattice.
The three-dimensional lattice structure is key to understanding the properties of network solids, such as their ability to withstand high temperatures and their overall rigidity.