Multiple Choice
The molecular geometry of the CHF3 molecule is ________, and the molecule is ________.
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12. Molecular Shapes & Valence Bond Theory
Molecular Geometry
Multiple Choice
What is the molecular geometry of CHF3 according to its Lewis structure?
A
Tetrahedral
B
Trigonal planar
C
Bent
D
Trigonal pyramidal
Verified step by step guidance1
Draw the Lewis structure of CHF3 by first counting the total valence electrons: Carbon has 4, Hydrogen has 1, and Fluorine has 7. So, total valence electrons = 4 (C) + 1 (H) + 3 × 7 (F) = 4 + 1 + 21 = 26 electrons.
Arrange the atoms with Carbon as the central atom because it is less electronegative than Fluorine. Connect Carbon to one Hydrogen and three Fluorine atoms with single bonds.
Distribute the remaining electrons to complete the octets of the Fluorine atoms. Each Fluorine needs 6 more electrons (3 lone pairs) to complete its octet, and Hydrogen only needs 2 electrons (already satisfied by the single bond).
Check the central atom Carbon: it forms four single bonds (one with H and three with F), so it has 4 regions of electron density around it.
Use VSEPR theory to determine the molecular geometry: with 4 bonding pairs and no lone pairs on the central atom, the shape is tetrahedral.
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