Polaridad y Geometría Molecular

• The objective of the class is to apply the VSEPR model to deduce molecular geometry.
• Another objective is to relate intermolecular forces to the chemical and physical properties of substances.
• Classifying molecular substances by geometry and resulting polarity is another objective.
• The goals also include identifying the different intermolecular forces present in substances.
• Describing the fundamental characteristics of different intermolecular forces is included.

Polaridad y Geometría Molecular

• Molecular geometry refers to the three-dimensional arrangement of atoms in a molecule
• Molecular geometry affects physical and chemical properties.
• RPECV refers to the "Modelo de la repulsión de los pares electronicos de la capa de valencia"
• RPECV stands for "Repulsion of the valence shell electronic pairs"

Átomo Central Sin Pares Libres (RPECV)

• Examples of central atoms without free pairs include BeCl₂, BF₃, CH₄, PCl₅, and SF₆.
• The geometry of BeCl₂ is linear, with 180° angle.
• The geometry of BF₃ is trigonal planar, with 120° angle.
• CH₄ is tetrahedral, with 109.5° angle.
• The geometry of PCl₅ is trigonal bipyramidal, with 90 and 120° angles.
• The geometry of SF₆ is octahedral, with 90° angles.

Átomo Central Con Uno o Más Pares Libres (RPECV)

• AB₂E, AB₃E, AB₂E₂, and AB₄E forms, where A is the central atom, B is a bonding atom, and E is a lone pair in the central atom, are studied in detail.
• Subscripts indicate the quantity of each.
• Repulsion hierarchy: lone pair vs. lone pair > lone pair vs. bonding pair > bonding pair vs. bonding pair
• Examples of AB₂E, AB₃E, AB₂E₂ include SO₂, NH₃, and H₂O respectively.

Molecular Polarity

• Covalent bonds can be polar or nonpolar.
• Bond polarities and molecular shape determine if a molecule is polar or nonpolar.
• Dipoles cancel in nonpolar molecules like CO₂ (linear) and CCl₄ (tetrahedral).
• Polar molecules, such as H₂O and NH₃, have dipoles that do not cancel each other.

Fuerzas Dipolo-Dipolo

• Dipole-dipole forces are attractive forces between polar molecules that possess dipole moments.
• A partially positive charge in one molecule is attracted to the partially negative charge in another.

Fuerzas Ion-Dipolo

• Ion-dipole forces attract an ion to a polar molecule.
• Interaction strength depends on the charge and size of the ion, and the magnitude of the dipole moment, and the size of the molecule.

Fuerzas de Dispersión

• Dispersion forces exist due to temporary dipoles.
• Dispersion forces increase with molar mass.

Puente de Hidrógeno

• Hydrogen bonding is a special type of dipole-dipole interaction.
• It occurs between a hydrogen atom bonded to N, O, or F and an electronegative atom (O, N, or F).