CHEM 1040 Lecture Notes - Lecture 7: Electronegativity, Diatomic Molecule, Sigma Bond

• School: University of Guelph
• Department: Chemistry
• Course: CHEM 1040
• Professor: Joe Prokipcak

Document Summary

Chem 1040- lecture 7- octet rule (continued) and molecular shapes & polarity. In the previous note, we discussed two failures to the octet rule; odd electrons systems and incomplete electron systems. The expanded electron system: the central atom has more than 8 electrons, can occur only with central atoms in at least the 3rd row, because the element must have a d orbital. Molecular shape and polarity: molecular shape and polarity can be determined from an atom"s lewis structure. 90, 180 bipyramid: molecular shapes can be described by, framework geometry: accounts for the total overall number of electron pairs, actual molecular shape: accounts for the free electron pairs and sigma bonds only. Molecular polarity: many chemical and physical properties rely on the polarity of a molecule, such as water solubility and boiling point, every bond is polar (unless diatomic, not every molecule has a net dipole. If the molecule is asymmetrical, it has a net dipole.