Question

name period identifying molecular geometry directions: draw the lewis structure of each molecule. use the molecular geometry chart to identify the shape name and bond angle of each molecule. h2o shape name: bond angle: pcl3 shape name: bond angle: bf3 shape name: bond angle:

Explanation:

Step1: Determine the electron - pair geometry and molecular geometry for \(H_2O\)

• Calculate the number of valence electrons: \(H\) has \(1\) valence electron and \(O\) has \(6\) valence electrons. For \(H_2O\), the total number of valence electrons is \(2\times1 + 6=8\).
• The Lewis structure of \(H_2O\) has \(O\) as the central atom. \(O\) forms two single bonds with \(H\) atoms and has two lone pairs.
• Using VSEPR (Valence - Shell Electron - Pair Repulsion) theory, the electron - pair geometry is tetrahedral (because there are \(4\) electron pairs around \(O\): \(2\) bonding pairs and \(2\) lone pairs).
• The molecular geometry (shape) is bent (or V - shaped). The bond angle is approximately \(104.5^{\circ}\) (due to the repulsion from the two lone pairs).

Step2: Determine the electron - pair geometry and molecular geometry for \(PCl_3\)

• Calculate the number of valence electrons: \(P\) has \(5\) valence electrons and \(Cl\) has \(7\) valence electrons. For \(PCl_3\), the total number of valence electrons is \(5+3\times7 = 26\).
• The Lewis structure of \(PCl_3\) has \(P\) as the central atom. \(P\) forms three single bonds with \(Cl\) atoms and has one lone pair.
• Using VSEPR theory, the electron - pair geometry is tetrahedral (because there are \(4\) electron pairs around \(P\): \(3\) bonding pairs and \(1\) lone pair).
• The molecular geometry (shape) is trigonal pyramidal. The bond angle is approximately \(100^{\circ}\) (due to the repulsion from the lone pair).

Step3: Determine the electron - pair geometry and molecular geometry for \(BF_3\)

• Calculate the number of valence electrons: \(B\) has \(3\) valence electrons and \(F\) has \(7\) valence electrons. For \(BF_3\), the total number of valence electrons is \(3 + 3\times7=24\).
• The Lewis structure of \(BF_3\) has \(B\) as the central atom. \(B\) forms three single bonds with \(F\) atoms and has no lone pairs.
• Using VSEPR theory, the electron - pair geometry and molecular geometry (shape) is trigonal planar. The bond angle is \(120^{\circ}\).

Answer:

• For \(H_2O\): Shape Name - Bent (V - shaped), Bond Angle - \(104.5^{\circ}\)
• For \(PCl_3\): Shape Name - Trigonal pyramidal, Bond Angle - \(100^{\circ}\)
• For \(BF_3\): Shape Name - Trigonal planar, Bond Angle - \(120^{\circ}\)