Question

Using Lewis symbols and Lewis structures, diagram the formation of \(\mathrm{SiCl}_{4}\) from \(\mathrm{Si}\) and \(\mathrm{Cl}\) atoms.

Short answer

The Lewis symbols for Si and Cl atoms are: Si: \(\cdot \overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Si}}} \cdot \) Cl: \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}} \longrightarrow \) The Lewis structure for \(\mathrm{SiCl}_{4}\) is: \(\mathrm{SiCl}_{4}\): \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}}\) - \(\cdot \overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Si}}} \cdot \) - \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}}\) | \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}}\) Silicon forms a single covalent bond with each of the four chlorine atoms, achieving a full octet for all atoms involved.

Step-by-step solution

Determine the Lewis symbols for Si and Cl atoms

To find the Lewis symbols, let's start by looking at the positions of both silicon (Si) and chlorine (Cl) in the periodic table. Silicon, with the atomic number 14, lies in Group 14 (or IV) and therefore has four valence electrons. Meanwhile, chlorine, with the atomic number 17, is in Group 17 (or VII) and has seven valence electrons. The Lewis symbols for the atoms are: Si: \(\cdot \overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Si}}} \cdot \) Cl: \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}} \longrightarrow \)

Combine the Lewis symbols to form the Lewis structure

In order to form a stable compound, silicon (Si) needs to achieve a full octet (eight electrons in its outermost shell), while each chlorine (Cl) atom also needs to reach a full octet. Silicon can do this by forming a single covalent bond with each of the four chlorine atoms, allowing both elements to share electrons and achieve a full outer shell. The Lewis structure for silicon tetrachloride will have Si at the center, bound to four Cl atoms: \(\mathrm{SiCl}_{4}\): \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}}\) - \(\cdot \overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Si}}} \cdot \) - \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}}\) | \(\overset{\displaystyle..}{\underset{\displaystyle..}{\mathrm{Cl}}}\) The structure above shows the silicon atom at the center, sharing one pair of electrons with each chlorine atom. This results in a complete octet for both Si and each Cl atom. Consequently, in \(\mathrm{SiCl}_{4}\), each chlorine atom forms a single covalent bond with the central silicon atom, satisfying the octet rule for all atoms involved and illustrating the formation of the compound using Lewis symbols and Lewis structures.

Key concepts

Covalent Bonding

Covalent bonding is a fundamental concept in chemistry where atoms share pairs of electrons to achieve stability. This type of bonding occurs primarily between nonmetal atoms, which need to fill their outer electron shells to become stable. For instance, in silicon tetrachloride (\(\text{SiCl}_4\)), silicon shares electrons with four chlorine atoms. Each covalent bond represents a shared pair of electrons, allowing all participating atoms to achieve a stable electronic configuration.

• Covalent bonds form when atoms share electrons.
• Occurs between nonmetal atoms.
• Aims to complete electron shells for stability.

The strength and number of covalent bonds determine the properties of the resulting compound. In \(\text{SiCl}_4\), the silica atom forms four single covalent bonds with chlorine atoms. This results in a stable molecular structure, demonstrating how covalent bonding enables the formation of complex chemical compounds.

Valence Electrons

Valence electrons refer to the electrons located in an atom's outermost shell. These electrons are crucial in determining how an atom will bond with other atoms. In the periodic table, elements are grouped based on the number of valence electrons they possess.
Silicon, which belongs to Group 14, has four valence electrons. This allows it to form four covalent bonds, as seen in \(\text{SiCl}_4\). Each chlorine atom, on the other hand, belongs to Group 17 and possesses seven valence electrons.

• Valence electrons are in the outermost shell of an atom.
• Determine bonding behavior of the atom.
• Group number in the periodic table is indicative of valence electrons.

Understanding valence electrons is key to predicting how atoms will interact. In silicon tetrachloride, silicon's four valence electrons pair with chlorine's seven valence electrons to complete their outer shells.

Octet Rule

The octet rule is a guiding principle in chemistry, stating that atoms tend to bond in a manner that provides them with eight electrons in their valence shell. This rule helps predict the chemical bonding behavior of atoms in molecules.
For silicon tetrachloride (\(\text{SiCl}_4\)), both silicon and chlorine adhere to the octet rule. Silicon starts with four valence electrons and forms four bonds with chlorine to complete its octet. Each chlorine atom then shares one of its seven valence electrons with silicon and "borrows" an additional electron from silicon, achieving a full outer shell of eight.

• Atoms strive to achieve eight electrons in their valence shell.
• Serves as a rule of thumb for predicting bonding behavior.
• Exceptions to the rule exist, but it supports the understanding of many compounds.

Silicon tetrachloride is an example of atoms achieving optimal stability by following the octet rule, ensuring the compound's structure is stable and bonded efficiently.

Silicon Tetrachloride

Silicon tetrachloride is a chemical compound composed of one silicon atom and four chlorine atoms, expressed as \(\text{SiCl}_4\). This compound is a clear illustration of covalent bonding principles and the fulfillment of the octet rule.
The structure of \(\text{SiCl}_4\) features the silicon atom centrally located, linked to four chlorine atoms. Each silicon-chlorine bond is a result of shared electron pairs—one from silicon and one from each chlorine. The sharing leads to both the silicon and chlorine atoms reaching full valence shells.

• Formula: \(\text{SiCl}_4\)
• Represents a tetrahedral geometry.
• A useful example of covalent bonding and the octet rule in action.

Silicon tetrachloride is not just important in academia, but also in industry, used in the production of high-purity silicon, essential for electronic devices. Its study aids in understanding molecular structure and stability derived from proper electron sharing and bonding.