ch 8 WEDNESDAY 3/21/12 Section 8.1Section 8.1The Covalent Bond Objective: To describe the formation & strength of covalent bonds Section 8.2 Naming Molecules Objective: To write names & formulae of molecules. Section 8.3 Molecular Structures Objective: To draw lewis structures of molecules. Section 8.4 Molecular Shapes Objective: To identify the shape of molecules based on hybridized orbitals. Section 8.5Electronegativity and Polarity Objective: To apply molecular shape and polarity to describe a molecules physical properties.

INTER- & INTRA- MOLECULAR FORCES

Background Knowledge spectrum (i.e. rainbows have a spectrum of colors) – continuous range the prefix “inter” (i.e. intercontinental) – between two different things the prefix “intra” (i.e. intramural sports) – within something the prefix “di” – two what hemisphere do polar bears live in? (northern or southern?) Symmetry

Ionic / Covalent Bond Spectrum The type of bond (ionic or covalent) depends on the strength of the intramolecular force. Intramolecular force – force of a bond between atoms IN a molecule - is determined by difference in electronegativity. Large Difference: Ionic Small Difference : Covalent ELECTRONEGATIVITY

Polarity & Polar Polar covalent bonds form when atoms pull on electrons in a molecule unequally. Electrons spend more time around one atom than another resulting in partial charges at the ends of the bond called a dipole.

Symmetry  NON-POLAR

Intermolecular Forces Forces that exist BETWEEN DIFFERENT MOLECULES. Relatively weak.

Intermolecular Forces

Bond Dipole and Molecular Dipole