Chapter 9 - Properties of Organic Compounds

Question 1

Describe dispersion

Answer 1

• non polar regions form instantaneous dipoles.

- weak but accumulative with more electrons

Question 2

Describe dipole-dipole

Answer 2

• polar molecules form permanent dipoles

- opposing charges on neighbouring molecules are electrostatically attracted to each other.

Question 3

Describe hydrogen bonding

Answer 3

-present when H is bonded to N,O,F. A neighbouring atom must also contain an electronegative element. These are the strongest due to hydrogens little shielding affect and small size.

Question 4

Describe flashpoint

Answer 4

The flashpoint of a volatile liquid is the lowest temperature at which the liquid gives off enough vapour to ignite. weaker intermolecular forces = lower flashpoint as molecule is more volatile

Question 5

Describe points

Answer 5

points refer to melting and boiling point. A high boiling point=strong intermolecular forces. A high melting point=more energy needed to push molecules away from each other.

Question 6

Describe viscosity

Answer 6

-the thickness of a substance (degree of flow)
high viscosity= very thick= no flow
low viscosity= not thick= lots of flow

Question 7

Hierarchy of hydrogen bonding and functional groups

Answer 7

carboxylic acids- QQQQQQQQQQQQQQQQ
alcohols-
amines/amides-
carbonyl/ester- only dipole
basic hydrocarbons- only dispersion

Question 8

What are structural isomers

Answer 8

structural isomers can be

• chain (different branching)
• positional (different position of functional group)
• functional (different functional group but same atoms)

Question 9

What is Stereoisomerism

Answer 9

where molecules are arranged differently around a double or triple bond. Only one common pair has to be used. CIS on the same side TRANS on opposite sides

Question 10

What is Enantiomerism (optical isomers)

Answer 10

• shown by a chiral centre
• mirror images are not superimposable
• carbon is bonded to 4 different molecules
• bend polarised light in opposing ways

Question 11

what are the functional isomer pairs?

Answer 11

alcohols—-ethers
carboxylic acids—-esters
aldehydes—-ketones