chapter 13 molecular shapes. molecular shape molecular shape or molecular geometry is the...
TRANSCRIPT
Chapter 13Molecular Shapes
Molecular Shape
• Molecular shape or molecular geometry is the three-dimensional arrangement of the atoms in a molecule.
Molecular Shape
• Molecular shape determines several properties of a substance including: – reactivity – polarity – phase of matter – color – magnetism – biological activity
Olfaction – sense of smell
• Lock-and-Key Theory: humans can smell various odors because each three-dimensional odor molecule fits into only one type of receptor.
Gustation – the sense of taste
• Taste receptors are located on the tongue and are sensitive to four major tastes: salty, sweet, sour and bitter.
• Taste receptors respond differentially to the varying shapes of food and liquid molecules.
H2
H H
2(1) = 2e-
Any 2 atoms
linear
What about molecules consisting of more than two atoms
Five Molecular Shapes
See the table in your notes
Steps in Determining Molecular Shape
1. Draw the Lewis Structure for the Molecule.
2. Count the number of atoms attached to the central atom.
3. Count the number of lone pairs attached to the central atom.
4. Use your counts on steps 2 and 3 to determine the shape of the molecule.
H2S
• Dihydrogen monosulfide or just hydrogen sulfide is also known as sewer gas. This colorless, toxic and flammable gas is responsible for the foul odor of rotten eggs.
H HS••
••
2(1)+6 = 8e-
2/2
angular
H2S
• Dihydrogen monosulfide or just hydrogen sulfide is also known as sewer gas. This colorless, toxic and flammable gas is responsible for the foul odor of rotten eggs.
H HS•• ••
Methane (CH4)4 + 4(1) = 8e-
Methane (CH4)4 + 4(1) = 8e-
4 atoms attached to the central atom.0 lone pairs on the central atom.4/0
Tetrahedral shape
Methane (CH4)4 + 4(1) = 8e-
4 atoms attached to the central atom.0 lone pairs on the central atom.4/0
Tetrahedral shape
HCN
H NC••
••
1+4+5 = 10e-
••
••
••
HCN
H NC••
••
1+4+5 = 10e-
••
••
••
HCN
H NC••
••
1+4+5 = 10e-
••
••
••
HCN
H NC••
1+4+5 = 10e-
••
••
HCN
H NC••
1+4+5 = 10e-
••
••
HCN
H NC
1+4+5 = 10e-
••
2/0
linear
H2S
H HS•• ••
2/2
angular
SO2
O OS••
••
6+2(6) = 18e-
••
••
••••
••••
SO2
O OS••
••
6+2(6) = 18e-
••
••
••••
••••
SO2
O OS••
••
6+2(6) = 18e-
••
••
••••
••••
2/1angular
CH4
4/0
tetrahedral
NO3-
O ON••
••
5+3(6)+1 = 24e-
••
••
••••
••••
O ••••
NO3-
O ON••
••
5+3(6)+1 = 24e-
••
••
••••
••••
O ••••
NO3-
O ON••
••
5+3(6)+1 = 24e-
••
••
••••
••••
O ••••
NO3-
O ON
5+3(6)+1 = 24e-
••
••
••••
••••
O •••• 3/0
trigonal planer
[ ]-
SOCl2
What’s the shape of acetate?
4/0
tetrahedral
3/0
trigonal planer
Homework
Worksheet Chapter 13.