Question

Draw the Lewis structures, predict the molecular structures, and describe the bonding (in terms of the hybrid orbitals for the central atom) for the following. a. \(\mathrm{XeO}_{3}\) d. \(\mathrm{XeOF}_{2}\) b. \(\mathrm{XeO}_{4}\) e. \(\mathrm{XeO}_{3} \mathrm{~F}_{2}\) c. \(\mathrm{XeOF}_{4}\)

Short answer

a. XeO3: T-shaped structure with d2sp3 hybridization. d. XeOF2: T-shaped structure with d2sp3 hybridization. b. XeO4: Tetrahedral structure with sp3 hybridization. e. XeO3F2: See-saw structure with dsp3 hybridization. c. XeOF4: Square pyramidal with dsp3 hybridization.

Step-by-step solution

a. XeO3 Lewis Structure

Step 1: Count the total number of valence electrons. Xe has 8 valence electrons and O has 6 valence electrons. Since there are 3 O atoms, the total number of valence electrons is \(8 + 3\times6 = 26\). Step 2: Write the electron configuration of the central atom (Xe). Xe has 5, 6, and 7 electron pairs (lone pairs and bonding pairs) on it. Step 3: Draw the Lewis structure. Put Xe in the center, and surround it with 3 O atoms. Create single bonds between Xe and O atoms, then add lone pairs to the O atoms to satisfy the octet rule. Finally, put the remaining 2 lone pairs on Xe. ``` O \ Xe == O / O ```

a. XeO3 Molecular Structure

The molecular structure can be predicted using the VSEPR theory. There are 3 bonding pairs and 2 lone pairs around the central atom (Xe). According to VSEPR theory, the shape is T-shaped because lone pairs will be on opposite sides to maximize the distance between them. Therefore, the bond angle between O-Xe-O is approximately 90 degrees.

a. XeO3 Hybrid Orbitals

In the T-shaped structure, we have 5 electron pairs around the Xe atom, so it uses the d2sp3 hybridization. This means there are 2 d orbitals, one s orbital, and 3 p orbitals involved in the hybridization. ---

d. XeOF2 - Lewis Structure, Molecular Structure, and Hybrid Orbitals

Lewis Structure: a. Total valence electrons: \(8 + 6 + 2\times7 = 28\) b. Electron configuration: 5, 6, and 7 electron pairs on Xe c. Arrange the single bonds and add lone pairs: ``` F - Xe - O - F ``` Molecular Structure: a. VSEPR theory: 3 bonding pairs and 2 lone pairs b. T-shaped structure, bond angle between O-Xe-F is approximately 90 degrees Hybrid Orbitals: d2sp3 hybridization ---

b. XeO4 - Lewis Structure, Molecular Structure, and Hybrid Orbitals

Lewis Structure: a. Total valence electrons: \(8 + 4\times6 = 32\) b. Electron configuration: 4 bonding pairs on Xe c. Arrange the single bonds and add lone pairs: ``` O | O-Xe-O | O ``` Molecular Structure: a. VSEPR theory: 4 bonding pairs b. Tetrahedral structure, bond angle between O-Xe-O is approximately 109.5 degrees Hybrid Orbitals: sp3 hybridization ---

e. XeO3F2 - Lewis Structure, Molecular Structure, and Hybrid Orbitals

Lewis Structure: a. Total valence electrons: \(8 + 3\times6 + 2\times7 = 36\) b. Electron configuration: 4, 5, and 6 electron pairs on Xe c. Arrange the single bonds and add lone pairs: ``` O | F - Xe - O | F ``` Molecular Structure: a. VSEPR theory: 4 bonding pairs and 1 lone pair b. See-saw structure, bond angle between O-Xe-F varies (roughly 90 and 120 degrees) Hybrid Orbitals: dsp3 hybridization ---

c. XeOF4 - Lewis Structure, Molecular Structure, and Hybrid Orbitals

Lewis Structure: a. Total valence electrons: \(8 + 6 + 4\times7 = 40\) b. Electron configuration: 5 and 6 electron pairs on Xe c. Arrange the single bonds and add lone pairs: ``` O | F - Xe - F / \ F F ``` Molecular Structure: a. VSEPR theory: 5 bonding pairs and 1 lone pair b. Square pyramidal, various bond angles (90 and 180 degrees). Hybrid Orbitals: dsp3 hybridization

Key concepts

VSEPR Theory

Understanding the shape of a molecule is crucial to predicting its properties and reactivity. The Valence Shell Electron Pair Repulsion (VSEPR) theory helps us predict molecular geometries based on the idea that electron pairs around a central atom will arrange themselves as far apart as possible to minimize repulsion. Let's break down this concept using a simple approach.

Firstly, consider each group of electrons, whether it's a single bond, double bond, triple bond, or a lone pair, as one region of electron density. The central atom is the atom we focus around to determine the shape. For instance, in the molecule XeO3, xenon (Xe) is the central atom and there are 3 bonding pairs (Xe-O bonds) and 2 lone pairs (unshared pairs of electrons).

Using the VSEPR theory, we predict that the molecule adopts a T-shaped structure because the 5 regions of electron density arrange themselves to minimize repulsion. This arranging of electron density defines the molecular structure and can help with understanding the chemical reactivity and physical properties of the molecule.

Hybrid Orbitals

The concept of hybrid orbitals is a key aspect of molecular bonding that provides insight into how atoms link together to form molecules. Hybridization describes the mixing of atomic orbitals to form new hybrid orbitals, which can then overlap to form covalent bonds. These hybrid orbitals have shapes and orientations unique to each type of hybridization, which allows for the formation of specific molecular geometries.

For example, in the molecule XeO3, the central atom xenon uses a set of hybrid orbitals known as d2sp3 to form T-shaped molecular geometry. This hybridization involves one s orbital, three p orbitals, and two d orbitals from the xenon atom, which mix to create hybrid orbitals that can house both bonding pairs and lone pairs. Understanding hybrid orbitals sheds light on how exactly bonding in complex molecules occurs beyond simple s and p orbital interactions.

Molecular Structure

Molecular structure encompasses not just the spatial arrangement of atoms but also the kind of bonds between them, reflecting both geometry and connectivity. It's vital for determining the physical and chemical properties of compounds. Through exercises like determining the structure of various Xe compounds, we learn about different molecular geometries such as T-shaped, tetrahedral, and see-saw structures, each associated with specific hybridization states of the central atom.

Moreover, the molecular structure influences properties like polarity, boiling and melting points, and reactivity. For instance, a molecule like XeOF4 exhibits a square pyramidal shape due to 5 bonding pairs and 1 lone pair of electrons around the central xenon atom. The lone pair's position leads to a nonuniform distribution of electron density, making the molecule polar. Grasping the concept of molecular structure is paramount for predicting how a molecule will interact with others, which is the essence of chemistry.