Lewis Structures and Molecular Shape

Lewis Dot Diagrams

Lewis Structures and Quantum Mechanics

Draw an orbital diagram to show the bonding in

H2O

Valence bond Theory (Pauling): covalent bonds share e- by

overlapping orbitals

p. 227 #4p. 230 #3

Lewis Structures

• Use the summaries on p. 225 and p. 229 to complete:p. 227 #5, p. 229 #10, 11, p. 230 #4,5p. 229 #12 (extension)

Draw Lewis diagrams of:

SbSr2+

Br-

CS2

NH4+

HPO32-

PCl5

Molecular Shapes and Optical Activity

• Unpolarized light (normal light) runs in all directions

• Polarization is confining the vibration of a wave to one direction

• Polarizer: a filter that only allows light waves in a particular direction to pass

• Various shapes will absorb and deflect the polarized light in different ways

Molecular Shapes Why do molecules take on these shapes?

Molecular Shape

VSEPR Theory• valence shell e- pairs repel each other

electrostatically so as to minimize repulsive forces• lone pairs are bulkier (occupy more space) and repel

bonded pairs of e- more strongly

Task:Build models of molecules in tables from p. 243-245 in text. Draw 3-D diagrams, write shape name and label bond angles for each molecule.

Homework

• p. 246 #1-4• p. 249 #10,11• p. 250 #1-3• p. 247 #9 (extension)