11 Questions
What is the primary assumption of the VSEPR model?
Electron pairs in the valence shell of a central atom repel each other.
What determines the bond angles in a molecule according to the VSEPR model?
The arrangement of electron pairs that minimizes repulsions.
Which of the following molecular shapes is characterized by a trigonal arrangement of electron pairs?
Trigonal planar
What is the ultimate goal of the electron pair arrangement in the VSEPR model?
To minimize electron pair-electron pair repulsions.
What is the valence shell in the context of the VSEPR model?
The outermost energy level of an atom.
Which of the following molecular shapes is typically associated with a polar molecule?
Tetrahedral
What is the primary focus of the VSEPR model in chemistry?
The bonding and nonbonding electron pairs present in the valence shell of an atom
What is the term for the outermost energy level of an atom that contains the valence electrons?
Valence shell
What is the result of unequal sharing of electrons in a polar molecule?
A separation of charge
What is the angle between any two bonds that include a common atom in a molecule?
Bond angle
What is required for a molecule to be considered polar?
A permanent dipole moment
Study Notes
VSEPR Theory
The Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used to predict the molecular structure, including approximate bond angles around a central atom, of a molecule from an examination of the number of bonds and lone electron pairs in its Lewis structure. The VSEPR model assumes that electron pairs in the valence shell of a central atom will adopt an arrangement that minimizes repulsions between these electron pairs.
Molecular Shapes
The VSEPR theory predicts the molecular shape based on the number of electron pairs (bond pairs and lone pairs) around the central atom. The shapes can be linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. Each of these shapes is characterized by specific bond angles and the distribution of electron pairs.
Electron Pair Repulsion
The VSEPR model is based on the assumption that electron pairs in the valence shell of a central atom will adopt an arrangement that minimizes repulsions between these electron pairs. The model assumes that electron pairs repel one another, producing a set of molecular geometries. The lowest-energy structure is the one that minimizes electron pair-electron pair repulsions.
Bond Angles
Bond angles in a molecule are determined by the VSEPR model. The theory assumes that the electron pairs repel each other, causing the arrangement of the atoms to adopt a geometry that minimizes these repulsions. In a molecule, bond angles are the angles between any two bonds that include a common atom, usually measured in degrees.
Valence Shell
The valence shell in chemistry refers to the outermost energy level of an atom, which contains the valence electrons. The VSEPR model focuses on the bonding and nonbonding electron pairs present in the valence shell of an atom.
Polarity
The VSEPR model does not directly predict the polarity of a molecule. However, it can be used in conjunction with other models, such as the Lewis electron-pair approach, to assess the polarity of a molecule. A molecule is considered polar if it has a permanent dipole moment, which arises from the electronegativity difference between atoms in a molecule. In a polar molecule, the sharing of electrons is not equal, resulting in a separation of charge that creates a net dipole. The VSEPR model can be used to predict the molecular geometry, which indirectly influences the polarity of the molecule.
Test your understanding of the VSEPR theory, which predicts the molecular structure and bond angles of a molecule based on the number of electron pairs in its Lewis structure. This quiz covers the basics of VSEPR, including molecular shapes, electron pair repulsion, and bond angles.
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