Questions and Answers
What are the 5 basic shapes of electron group geometries?
What is the geometry of 2 electron groups?
Linear
What is the geometry for 4 electron groups?
Tetrahedral
What is the geometry for 5 electron groups?
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What is the geometry for 6 electron groups?
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What do electron groups do to minimize repulsion?
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What is linear geometry characterized by?
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Define electron group.
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What is the bond angle for trigonal planar geometry?
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What is the bond angle for tetrahedral geometry?
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What is molecular geometry determined by?
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If all groups are bonding groups, electron-group geometry is equal to molecular geometry.
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What does VSEPR stand for?
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What is the molecular geometry for AX3E?
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Describe the effect of lone pairs on tetrahedral electron group geometry.
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What is hybridization?
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What is a sigma bond?
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What is a pi bond?
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What does molecular orbital theory state about O2's magnetism?
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Define bond order.
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Study Notes
Electron Group Geometries
- Five basic shapes of electron group geometries: linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral.
- Linear geometry occurs with 2 electron groups resulting in 180-degree bond angles.
- Tetrahedral geometry forms with 4 electron groups, with bond angles of 109.5 degrees.
- Trigonal bipyramidal geometry is characterized by 5 electron groups, with 120-degree angles in the equatorial plane and 90-degree angles in the axial positions.
- Octahedral geometry involves 6 electron groups, all at 90-degree bond angles.
Electron Group Interactions
- Electron groups arrange to minimize repulsion, placing themselves as far apart as possible.
- The presence of lone pairs affects angles due to increased repulsion compared to bonding pairs.
Molecular Geometry Concepts
- Molecular geometry, which refers to the shape formed by bonding groups, can differ from electron-group geometry if lone pairs are present.
- VSEPR notation uses A for central atom, X for bonding groups, and E for lone pairs to signify geometry.
Hybridization and Bonding
- Hybridization involves mixing atomic orbitals to form equivalent hybrid orbitals, leading to specific molecular shapes.
- Sigma bonds are formed from the head-on overlap of orbitals, while pi bonds arise from the side-by-side overlap of unhybridized p orbitals, allowing for multiple bonding scenarios.
- sp, sp2, and sp3 hybridizations correspond to linear, trigonal planar, and tetrahedral geometries, respectively.
Molecular Orbital Theory
- Molecular orbital theory describes electrons as delocalized over the entire molecule rather than localized to individual atoms.
- Bonding orbitals are formed by constructive interference, while antibonding orbitals arise from destructive interference.
- Bond order is calculated to indicate the strength and stability of bonds: single (1), double (2), triple (3), and the possibility of no bond (0).
Geometries and Isomerism
- Geometric isomers arise due to the rigidity of double bonds, resulting in different spatial arrangements (cis and trans forms).
- Structural isomers differ in the arrangement of atoms but contain the same molecular formula.
Key Factors in Bonding
- The strength of interactions between electron groups follows the order: lone pair-lone pair (LP-LP) repulsions > lone pair-bonding pair (LP-BP) repulsions > bonding pair-bonding pair (BP-BP) repulsions.
- The position of lone pairs is optimized to minimize repulsive interactions, significantly influencing molecular shape and bond angles.
Parameters and Predictions
- Steps to predict shapes around central atoms include drawing Lewis structures, counting electron groups, classifying groups, and determining molecular geometry through VSEPR notation.
- Three-dimensional structures of larger molecules treat interior atoms as central atoms to assess the geometry around each.
Final Concepts
- Polar molecular geometries include those with asymmetric distributions such as bent and trigonal pyramidal shapes.
- Both paramagnetism and diamagnetism are explained through molecular orbital theory, showcasing the importance of unpaired electrons in molecular behavior.
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Description
Test your knowledge of electron group geometries with these flashcards from General Chemistry Chapter 10. This quiz covers the five basic shapes of electron group geometries including linear, tetrahedral, and octahedral. Perfect for students looking to reinforce their understanding of molecular geometry.