Question

answer the questions in the table below about the shape of the phosphorus pentafluoride (pf₅) molecule.

what word or two - word phrase best describes the shape of the pf₅ molecule?

what is the angle between the phosphorus - fluorine bonds? (if there is more than one angle, pick the smallest.)

Explanation:

For the first question (molecular shape of \( PF_5 \)):

To determine the shape of \( PF_5 \), we use the VSEPR (Valence Shell Electron Pair Repulsion) theory. The central phosphorus atom has 5 valence electrons, and it forms 5 single bonds with fluorine atoms (each fluorine contributes 1 electron for bonding). So, the electron - pair geometry and molecular geometry (since there are no lone pairs on the central atom) is determined by 5 bonding pairs. The molecular shape corresponding to 5 bonding pairs (trigonal bipyramidal geometry) has a molecular shape described as trigonal bipyramidal.

In the trigonal bipyramidal structure of \( PF_5 \), there are two types of bond angles: the equatorial - equatorial bond angle (between the three equatorial fluorine atoms) is \( 120^{\circ} \), and the axial - equatorial bond angle (between an axial fluorine atom and an equatorial fluorine atom) is \( 90^{\circ} \). Since we need the smallest angle, we choose \( 90^{\circ} \).

Answer:

trigonal bipyramidal

For the second question (smallest bond angle in \( PF_5 \)):