Question

What is the Lewis electron dot diagram of \(\mathrm{SiF}_{4}\) ? Circle the electrons around each atom to verify that each valence shell is filled.

Short answer

SiF₄ has Si in the center with four F atoms each with 3 lone pairs around it, forming single bonds.

Step-by-step solution

Determine Valence Electrons

Count the valence electrons for each element in \(\text{SiF}_4\). Silicon (Si) has 4 valence electrons, and fluorine (F) has 7 valence electrons. Since there are four fluorine atoms, there are a total of \(4 + 4\times 7 = 32\) valence electrons to distribute.

Determine the Central Atom and Draw Skeleton Structure

Identify the central atom, which is typically the less electronegative element; here it's silicon (Si). Draw Si in the center with four fluorine atoms (F) surrounding it, each connected by a single bond.

Distribute Electrons to Form Bonds

Allocate electrons to form bonds between Si and each F atom. Each single bond consists of 2 electrons. Thus, 4 bonds use \(4 \times 2 = 8\) electrons out of the 32 total.

Complete the Octets for Fluorine Atoms

Each F atom needs 8 electrons to complete its octet. Since each F atom is already using 2 electrons in the bond with Si, place 6 additional electrons (three pairs) around each F atom. This uses \(4 \times 6 = 24\) more electrons.

Verify the Octet Rule for Silicon

Check that Si shares 8 electrons. Si is bonded with four F atoms, and each bond shares 2 electrons, resulting in 8 electrons around Si. Thus, Si's valence shell is also full.

Finalize the Electron Dot Diagram

Draw the complete Lewis structure. Place Si in the center and surround it with the four F atoms. Each F atom has 3 pairs of dots (representing its lone pairs) and a line connecting it to the Si, indicating a bond.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons found in an atom's shell and play a crucial role in forming chemical bonds. These electrons are primarily responsible for the chemical behavior of the elements and participate in bonding with other atoms.

• For example, silicon (Si) in \( ext{SiF}_4\) has 4 valence electrons, because it is in Group 14 of the periodic table.
• Fluorine (F), on the other hand, has 7 valence electrons, as it belongs to Group 17.

In the compound \( ext{SiF}_4\), we have a total of 32 valence electrons to consider when drawing the Lewis dot diagram. This total comes from adding the 4 valence electrons from silicon and 28 from the four fluorine atoms. It is essential to correctly count and distribute these electrons to ensure the atoms form stable and complete valence shells.

Octet Rule

The octet rule is a fundamental concept in chemistry that helps us predict how atoms will bond with each other. Essentially, it states that atoms tend to bond in such a way that they each have eight electrons in their valence shell, similar to the stable configuration of a noble gas.

• Each fluorine atom in \( ext{SiF}_4\) needs 8 electrons to fulfill the octet rule, which it achieves by forming a single covalent bond with silicon and holding three pairs of non-bonding electrons.
• Silicon achieves its octet by sharing four of its electrons with four fluorine atoms, thereby also completing its valence shell with 8 electrons shared in total.

The octet rule is a helpful guideline, though there are exceptions, especially with elements that can have expanded octets, like silicon in other compounds. However, in \( ext{SiF}_4\), both Si and F adhere to this rule neatly, allowing us to predict a stable molecule correctly.

Chemical Bonds

Chemical bonds are the forces that hold atoms together within a molecule. In the context of \( ext{SiF}_4\), we are primarily concerned with covalent bonds, which involve the sharing of electron pairs between atoms.

• Each silicon-fluorine connection in \( ext{SiF}_4\) is a covalent bond, formed by sharing a pair of electrons. This ensures that each atom can reach a stable electron configuration.
• These bonds help to fill the valence shells of both silicon and fluorine, making them stable according to the octet rule.

Understanding how these bonds form and their nature is crucial for drawing the Lewis electron dot diagram, which visually represents these electron sharing arrangements. Recognizing that \( ext{SiF}_4\) has four single covalent Si-F bonds helps to decipher its structural imaging and predict its chemical behavior.