Question

For each of the following, write the Lewis structure(s), predict the molecular structure (including bond angles), and give the expected hybridization of the central atom. a. \(\mathrm{KrF}_{2}\) b. \(\mathrm{KrF}_{4}\) c. \(\mathrm{XeO}_{2} \mathrm{~F}_{2}\) d. \(\mathrm{XeO}_{2} \mathrm{~F}_{4}\)

Short answer

a. KrF2: Linear molecular structure with a 180° bond angle, central Kr atom is sp2 hybridized. b. KrF4: Square planar molecular structure with 90° bond angles, central Kr atom is sp3d2 hybridized. c. XeO2F2: See-saw molecular structure with 120° and 90° bond angles, central Xe atom is sp3d hybridized. d. XeO2F4: Distorted octahedral molecular structure with 180° and 90° bond angles, central Xe atom is sp3d2 hybridized.

Step-by-step solution

a. KrF2 Lewis structure

We start by writing the Lewis structure of KrF2. Kr has 8 valence electrons, and F has 7. As Kr is the central atom, it will be bonded to both F atoms. The two remaining valence electrons on Kr will form a lone pair. The F atoms have three lone pairs each. The Lewis structure looks like this: ``` F - Kr - F :__:__, ```

a. KrF2 Molecular structure and bonding angles

KrF2 has a linear molecular structure. There are 3 electron groups on the Kr atom (2 bonding pairs and 1 lone pair), resulting in a trigonal planar electron geometry. However, the lone pair will not influence the molecular geometry, so the bonding angle between the F atoms is 180°.

a. KrF2 Hybridization of the central atom

Since there are 3 electron groups around the central atom (Kr), it is sp2 hybridized.

b. KrF4 Lewis structure

For KrF4, we write the Lewis structure as follows, with 4 F atoms bonded to the Kr atom: ``` F : F-Kr-F : F ```

b. KrF4 Molecular structure and bond angles

KrF4 has a square planar molecular structure, with 90° bond angles between the F atoms. The central atom has 8 electrons; 4 electrons are used for Kr-F bonds, and the remaining 4 electrons form two lone pairs.

b. KrF4 Hybridization of the central atom

With 4 bonding pairs and 2 lone pairs, the central atom Kr has 6 electron groups, which means it is sp3d2 hybridized.

c. XeO2F2 Lewis structure

For XeO2F2, the Lewis structure shows 2 O atoms and 2 F atoms bonded to the central Xe atom: ``` O = Xe - F :,:: :,_ F ```

c. XeO2F2 Molecular structure and bonding angles

XeO2F2 has a see-saw or distorted tetrahedral molecular structure. The bond angles between the O atoms and Xe atom is about 120°, while the bond angles between the F atoms and Xe atom are about 90°.

c. XeO2F2 Hybridization of the central atom

The central atom Xe has 5 electron groups: 2 O bonding pairs, 2 F bonding pairs, and 1 lone pair. Therefore, it is sp3d hybridized.

d. XeO2F4 Lewis structure

For XeO2F4, we have 2 O atoms and 4 F atoms bonded to the central Xe atom: ``` O = Xe - F :,:::,:_ F F ```

d. XeO2F4 Molecular structure and bond angles

In XeO2F4, we have an octahedral electron geometry with 6 electron groups around the central atom (Xe). However, since the O and F atoms are different, the molecular structure will be distorted octahedral. The bond angle between the O atoms and Xe atom is 180°, while the bond angles between the F atoms and Xe atom are about 90°.

d. XeO2F4 Hybridization of the central atom

With 6 bonding pairs, the central Xe atom is sp3d2 hybridized.