Polymers & Exam 3 Essay Questions - Chem

Polymer

long chain molecules made up of repeating units

Monomers

repeating units which can link to form polymers

Addition polymers

polymers constructed without any loss of mass from the monomer

• monomers will always have a multiple bond

• 4 carbon backbone

Condensation polymers

polymers formed with a loss of a small molecule 

• backbone: carbonyl containing and non-carbonyl containing group

Carbonyl group

C double bonded to an O

By looking at the name of a molecules, how can you tell if they are structural isomer?

You can tell if a molecule is a structural isomer if they have the same molecular formula but different connectivity.

How can you tell if molecules are geometric isomers?

differs across a rigid plane by cis/trans

How can you tell if molecules are enantiomers?

opposite configuration (R,S) and have a nonsuperimposable mirror image

How can you tell if molecules are non-geometric diastereomers?

must be nonsuperimposable, NOT mirror images of each other, at least two chiral centers with one same and one different configuration

What does it mean for a molecule to be chiral?

Has a nonsuperimposable mirror image

What does it mean to have a chiral carbon

a central carbon must be sp3 hybridized 

4 unique groups surrounding it 

no double bonds

no heteroatoms

Is it possible to have chiral carbons but be an achiral molecule?

Yes but there must be an INTERNAL plane of symmetry

ex: meso compounds (even number of chiral centers, internal plane of symmetry, opposite configuration, same groups attached)

Optically active

molecule can be rotated around plane polarized light

What makes a polymer rigid?

strong IMFs —> tightly packed molecules

What makes a polymer flexible?

weaker IMFs —> loosley packed molecules (freedom of movement)