Draw the Lewis structure for each of the following molecules or ions, and predict their electron-domain and molecular geometries: (e) XeF2

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons. Xenon (Xe) has 8 valence electrons and each Fluorine (F) atom has 7 valence electrons. Since there are 2 Fluorine atoms, the total number of valence electrons is 8 + 2*7 = 22.
2. Step 2: Draw a skeleton structure of the molecule. Xenon (Xe) is the central atom and is surrounded by the two Fluorine (F) atoms. Connect each Fluorine atom to the Xenon atom with a single bond (which represents 2 electrons).
3. Step 3: Distribute the remaining electrons as lone pairs on the surrounding atoms first and then on the central atom. Each Fluorine atom needs 6 more electrons to complete its octet, which uses up 12 electrons. The remaining 8 electrons are placed on the central Xenon atom as 4 lone pairs.
4. Step 4: Check if all atoms have a complete octet. In this case, Xenon has more than 8 electrons which is possible because it can have an expanded octet.
5. Step 5: Determine the electron-domain geometry and the molecular geometry. The electron-domain geometry is based on the number of electron domains (regions of high electron density). In XeF2, there are 3 electron domains (2 bonding domains and 1 nonbonding domain), so the electron-domain geometry is trigonal planar. The molecular geometry is based on the number of bonding domains. In XeF2, there are 2 bonding domains, so the molecular geometry is linear.

Key Concepts

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They use dots to represent valence electrons and lines to represent bonds between atoms. Understanding how to draw Lewis structures is essential for predicting molecular geometry and reactivity.

Electron-Domain Geometry

Electron-domain geometry refers to the spatial arrangement of all electron domains (bonding and lone pairs) around a central atom. This concept is crucial for determining the overall shape of a molecule, as it considers both bonded atoms and lone pairs, which can influence the angles between bonds.

Molecular Geometry

Molecular geometry describes the three-dimensional arrangement of atoms in a molecule, focusing only on the positions of the atoms and not the lone pairs. It is derived from the electron-domain geometry and helps predict the physical and chemical properties of the molecule, such as polarity and reactivity.