Multiple Choice
The ammonia molecule (NH_3) in the diagram has the observed bond orientation because:
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12. Molecular Shapes & Valence Bond Theory
Molecular Geometry
Multiple Choice
What is the molecular geometry of PF_3?
A
Trigonal pyramidal
B
Tetrahedral
C
Bent
D
Trigonal planar
Verified step by step guidance1
Identify the central atom in PF_3, which is phosphorus (P).
Determine the number of valence electrons for phosphorus (5) and fluorine (7 each), then calculate the total valence electrons for the molecule: 5 + 3 × 7 = 26 electrons.
Draw the Lewis structure by placing phosphorus in the center bonded to three fluorine atoms, and then distribute the remaining electrons to satisfy the octet rule, noting that phosphorus has one lone pair of electrons.
Count the regions of electron density (bonding pairs and lone pairs) around the phosphorus atom. There are three bonding pairs and one lone pair, making a total of four regions.
Use VSEPR theory to determine the molecular geometry based on four regions of electron density with one lone pair, which results in a trigonal pyramidal shape.
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