Multiple Choice
Which two theories are commonly used to predict the molecular geometry of a molecule?
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12. Molecular Shapes & Valence Bond Theory
Molecular Geometry
Multiple Choice
If a molecule has a tetrahedral shape, how many lone pairs are most likely present on the central atom?
A
2
B
3
C
0
D
1
Verified step by step guidance1
Recall that a tetrahedral molecular shape typically arises when the central atom has four regions of electron density around it, all of which are bonding pairs.
Understand that lone pairs on the central atom affect the molecular geometry by repelling bonding pairs and changing the shape from ideal geometries like tetrahedral to others such as trigonal pyramidal or bent.
Recognize that the ideal tetrahedral shape corresponds to four bonding pairs and zero lone pairs on the central atom, as lone pairs would distort the shape.
Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to confirm that zero lone pairs on the central atom result in a tetrahedral geometry with bond angles close to 109.5°.
Conclude that if a molecule is described as having a tetrahedral shape, the central atom most likely has 0 lone pairs.
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