Consider the molecule \(\mathrm{PF}_{4}\) Cl. (a) Draw a Lewis structure for the molecule, and predict its electron-domain geometry. (b) Which would you expect to take up more space, a \(\mathrm{P}-\mathrm{F}\) bond or a \(\mathrm{P}-\mathrm{Cl}\) bond? Explain. (c) Predict the molecular geometry of \(\mathrm{PF}_{4} \mathrm{Cl}\). How did your answer for part (b) influence your answer here in part (c)? (d) Would you expect the molecule to distort from its ideal electron-domain geometry? If so, how would it distort?

To draw the Lewis structure, first identify the central atom. Here, the central atom is phosphorus (P). There are four fluorine (F) atoms and one chlorine (Cl) atom bonded to the P atom. The valence electrons in each atom are as follows: P has 5, each F has 7, and Cl has 7. Therefore, the total number of valence electrons is 5 + 4(7) + 7 = 5 + 28 + 7 = 40. Arrange the F and Cl atoms around the P atom in a way that best minimizes electron repulsion, and draw single bonds between the P atom and the 5 surrounding atoms. Distribute the remaining valence electrons as lone pairs to complete the octets for all atoms (except P, which has an expanded octet). The resulting Lewis structure can be represented as P in the center, bonded to four F atoms, and then to one Cl atom. Next, determine the electron-domain geometry based on the number of electron groups around the central atom. In this case, P has a total of 5 electron groups (4 P-F bonds and 1 P-Cl bond), which indicates a trigonal bipyramidal electron-domain geometry. #Step 2: Comparing P-F and P-Cl Bond Sizes#

The bond size can be determined by comparing the atomic radius of the involved atoms. Generally, larger atomic radius leads to larger bond size. The atomic radius of chlorine is greater than that of fluorine, so we can expect that a P-Cl bond will take up more space compared to a P-F bond. #Step 3: Predicting the Molecular Geometry of PF4Cl#

In a trigonal bipyramidal electron-domain geometry, there are two axial positions and three equatorial positions. As the P-Cl bond takes up more space, it is likely to be placed in an equatorial position to minimize repulsions. Therefore, the molecular geometry of PF4Cl will have Cl in one equatorial position, and the F atoms will occupy the two axial and the remaining two equatorial positions. The molecular geometry can be described as a seesaw or distorted tetrahedron. #Step 4: Distortion from Ideal Electron-Domain Geometry#

Yes, the molecule will likely distort from its ideal trigonal bipyramidal electron-domain geometry due to the differences in size and electronegativity of the F and Cl atoms. The distortion will result in a molecular geometry like a seesaw, where the Cl atom is in an equatorial position and the F atoms occupy the two axial and the remaining two equatorial positions. This distortion occurs to minimize electron repulsion caused by the larger P-Cl bond and the differences in electronegativity between the F and Cl atoms.