unit 2 - structure

Question 1

how do you classify the functional group based on degree of substitution?

Answer 1

• how much other groups that carbon the is attached with the function group has

Question 2

What are the different functional groups

Question 3

Physical Propertites and molecular structure: intermolecular forces

What are Van der waals forces?

Answer 3

• attractive or repulsive interactions b/w or within molecules
• refers to all interactions that are not iconic
• use the example of water: ice -> liquid -> gas
• what keeps the water molecules tgt?

Question 4

Physical Propertites and molecular structure: intermolecular forces

Describe Ionic Interactions

Answer 4

• generally strong
• interactions b/w 2 speices of opposite charge
• Na-Cl

Question 5

Physical Propertites and molecular structure: intermolecular forces

Describe Dipole-Dipole Interactions

Answer 5

• summantion of all the bond polarities of a molecule resulting from differences in EN b/w bonded atoms
• molecules in which bond polarities are in exactly opposite directions possess no dipole moment = all bond dipoles cancel
• relates to boiling point, if dipole has a harder time pulling molecules apart
• weaker interactions than ionic interactions

Question 6

Physical Propertites and molecular structure: intermolecular forces

Describe Hydrogen-bonds (H-bonds)

Answer 6

• interaction b/w H attached to O and N with non-bonding electrons
• stronger than dipole-dipole but weaker than ionic interactions

Question 7

Physical Propertites and molecular structure: intermolecular forces

Describe London/Dispersion forces

Answer 7

• temporary dipole(s) or polarizations in a molecule that result from molecular distortions and induce a temporary dipole
• weakest of all intermolecular forces

Question 8

Physical Propertites and molecular structure

What are the trends for m.p and b.p

Answer 8

• Increasing molecular weight = increase w b.p and m.p
• bond connectivity (floopyness) the geometry = increase with b.p
• significant ontermolecular ionic interactions = high bp and mp
• increasing amounts of dipole-dipole or H-bonding interactions = increase mp/bp
• packing: spaghetti vs meatball (meatball wins lolol) = higher mp

• big alkyl substituents can mask the properties of polar functional groups

Question 9

IR Spectroscopy

what does the position of absorportion depend on?

Answer 9

1. type of absorportion (bending vs stretching)
2. Atoms connected by the bond

Question 10

IR Spectroscopy

What are the general trends seen?

Answer 10

• stretching requires more enger than bending = more stretching occurs at higher wavenumbers
• the stronger the bond the higher energy the stretching

Question 11

IR Spectroscopy

What are the regions

Answer 11

1. Fingerprint Region (below 1500 cm-1)
2. Functional Group Region (4000cm-1-1400cm-1)

Question 12

IR Spectroscopy

Label the important absorption regions