Lewis Structures and Molecular Shape. Lewis Dot Diagrams.

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)