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Questions and Answers
According to VSEPR theory, what primarily determines the shape of a molecule?
According to VSEPR theory, what primarily determines the shape of a molecule?
In a molecule, how does the spatial requirement of a lone pair of electrons compare to that of a bonding pair?
In a molecule, how does the spatial requirement of a lone pair of electrons compare to that of a bonding pair?
What is the molecular geometry of $BeH_2$?
What is the molecular geometry of $BeH_2$?
Which of the following molecules has a bent geometry?
Which of the following molecules has a bent geometry?
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How many lone pairs of electrons are present on the central atom in $CH_4$?
How many lone pairs of electrons are present on the central atom in $CH_4$?
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Which of the following describe a molecule with a central atom that has 3 bonding pairs and zero lone pairs?
Which of the following describe a molecule with a central atom that has 3 bonding pairs and zero lone pairs?
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Which of these statements is a correct VSEPR theory description for a molecule that has a central atom with 2 bonding pairs and 2 lone pairs?
Which of these statements is a correct VSEPR theory description for a molecule that has a central atom with 2 bonding pairs and 2 lone pairs?
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Study Notes
Molecular Shapes
- Knowing a compound's shape is crucial because it dictates how it interacts with other molecules.
- VSEPR (Valence Shell Electron Pair Repulsion) theory helps predict molecular structures.
- VSEPR formula is a structural formula illustrating 3D arrangement of peripheral groups.
- Electron pairs repel each other, so bonding pairs and lone pairs are positioned as far as possible.
- Lone pairs take up more space than bonding pairs.
- The number of electron pairs equals the number of bonded atoms plus the number of lone pairs.
Types of Molecular Shapes
- Linear: central atom with 2 bonding pairs (e.g., BeH₂ , CO₂)
- Bent: central atom with 2 bonding pairs and 2 lone pairs (e.g., H₂O)
- Trigonal planar: central atom with 3 bonding pairs (e.g., BF₃)
- Trigonal pyramidal: central atom with 3 bonding pairs and 1 lone pair (e.g., NH₃)
- Tetrahedral: central atom with 4 bonding pairs (e.g., CH₄)
Diagram Conventions
- Lines (or wedges): atoms in the plane of the page
- Dashed lines: atoms behind the plane of the page
- Solid wedges: atoms in front of the plane of the page
- Using these conventions for diagrammatic representation is important to understand 3D arrangement.
Determining Molecular Shape
- Count the number of bonding pairs and lone pairs of electrons around the central atom.
- The arrangement of electron pairs dictates the molecule's shape.
- Refer to the table to determine the name of the geometry based on the number of bonding and non-bonding pairs..
Additional Compounds
- The study includes a list of compounds for which Lewis, structural, and VSEPR diagrams need to be drawn. Examples include H₂Te, Si₂ , CHCl₃, PH₃, CS₂, and CH₃COH. Additional practice problems are in workbook #10.
Workbook #9
- A possible workbook assignment is referenced.
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Description
Explore the concepts of molecular shapes and the VSEPR theory that predicts the 3D arrangement of molecules. This quiz covers various molecular geometries such as linear, bent, trigonal planar, and tetrahedral forms. Understanding these shapes is essential for grasping how molecules interact.
