Module 2b: Techniques for Material Characterization

Question 1

GOODNOTES -> based off slide 3, draw the general structure of an amorphous material and a crystalline material, as well as a semi-crystalline material

Answer 1

completed

Question 2

Describe the process to find the Miller Indice of a crystalline plane

Answer 2

1. find the intercepts on the x, y, and z axis
2. take reciprocals of the intercepts
3. clear fractions
4. reduce to lowest terms

Answer will be in the form of this example: (341)
x = 3, y = 4, z =1

Question 3

What are the Miller Indices for a plane with intercepts (1/3, 2/3, 1/2)?

Answer 3

(634)

Question 4

Can Miller Indices be negative?

Answer 4

Yes! If the intercept is along the negative axis, the Miller Indice can be negative

Question 5

GOODNOTES -> what are the miller indices of the plane in slide 8?

Answer 5

(101)

Question 6

GOODNOTES -> draw the spectroscopy tree diagram on slide 11

Answer 6

completed

Question 7

Application of spectroscopy so that there are QUANTIFIABLE RESULTS that can be assessed

Answer 7

Spectrometry

Question 8

How compounds absorb different types of energy. Excitation of samples lead to change in electron or mechanical motion within the molecule

Answer 8

Spectroscopy

Question 9

A plot showing the response (absorbance, emission, or intensity) as a function of wavelength, frequency, or mass/charge ratio)

Answer 9

Spectrum

Question 10

GOODNOTES -> using the tree drawn on slide 10 (skip if this hasn’t been reached yet), write descriptions of the techniques used in spectroscopy

Answer 10

completed

Question 11

Measurement of absorbed wavelengths by sending light through a sample

Answer 11

UV/VIS spectrophotometer

Question 12

What is a UV-VIS spectrophotometer used to find?

Answer 12

Concentration and molecular structure

Question 13

The wavelength and amount of light that a compound absorbs depends on its m____ s_____ and the c_____ of the compound used

Answer 13

Wavelength and amount of absorbed light is dependent on the molecular structure and concentration of the compound

Question 14

Which law does UV-VIS spectrophotometry use?

Answer 14

Beer Lambert’s Law

Question 15

A = epsilon * c * l is which equation? What do the variables represent?

Answer 15

Beer Lambert’s Law
A = absorbance
l = path length (thickness) of the sample solution (cm)
c = molar concentration of sample solution (mol/L)
epsilon = molar absorption coefficient

Question 16

How do you read a UV-VIS spectrophotometer graph?

Answer 16

There is a sharp peak at max absorbance

Question 17

GOODNOTES -> view slide 19; which sample has the highest absorbance? What is the highest absorbance?

Answer 17

the 25 microM has the highest absorbance at 2.5, at a wavelength of ~550 nm

Question 18

Can UV-VIS spec be used to monitor enzyme reactions? If so, how?

Answer 18

Yes! It can be beneficial in monitoring enzyme reactions because it measures changes in substrate/product absorbance

Question 19

Atoms diffract x-rays differentially

Answer 19

X-ray diffraction

Question 20

What is x-ray diffraction used to find?

Answer 20

Miller indices and crystal coordinate systems

Question 21

How do you read an x-ray diffraction visual?

Answer 21

Look at the diffraction angle (this is double theta), this is the angle between the incident x-ray beam and the scattered / diffracted x-ray beam

Question 22

A polycrystalline sample should contain thousands of crystallites; should all possible diffraction peaks be observed?

Answer 22

Yes!

Question 23

For every set of planes, there will be a ____ percentage of crystallites that are properly oriented to diffract (the plane perpendicular bisects the incident and diffracted beams)

Answer 23

Small

Question 24

Can X-ray diffraction be used to identify the composition of materials and the quality of the crystal?

Answer 24

Yes!

Question 25

T/F: X-ray diffraction can't be used to understand biological processes and design new drugs

Answer 25

FALSE! X-ray diffraction CAN be used to understand biological processes and design new drugs

Question 26

GOODNOTES -> on slide 21, complete the sample question

Answer 26

complete

Question 27

Covalent bonds vibrate at certain frequencies?

Answer 27

IR spectroscopy

Question 28

Covalent bonds vibrate only at certain frequency. What is the relationship between frequency and increasing atomic weight and bond energy?

Answer 28

Increasing bond energy -> increases frequency Increasing atomic weight -> decreases frequency

Question 29

Why does an increase in bond energy correspond to an increase in frequency?

Answer 29

Higher bond energy means stronger bonds. These stronger bonds are more stiff and harder to stretch (more vibration)

Question 30

Why does frequency decrease with increasing atomic weight?

Answer 30

Heavier atoms have more mass and vibrate slower

Question 31

What is IR spectroscopy used to find?

Answer 31

Functional groups attached to organic molecules

Question 32

Can IR spectroscopy be used to assess the degree of polymerization?

Answer 32

Yes!

Question 33

IR spectroscopy along cannot determine the _______ of a molecule

Answer 33

Structure

Question 34

GOODNOTES -> complete the IR spectra example problem on slide 26

Answer 34

completed

Question 35

Do ring based molecules have larger dips in the 3000 cm-1 range?

Answer 35

Yes!

Question 36

How do you read IR Spectroscopy charts?

Answer 36

Find the peaks, and use the table to determine the functional groups from the peaks

Question 37

Spinning charged nuclei to create a magnetic field to shield the protein, which can be measured

Answer 37

Nuclear magnetic resonance (NMR) spectroscopy

Question 38

What is nuclear magnetic resonance (NMR) spectroscopy used to find?

Answer 38

The structure and location of protons in an organic molecule

Question 39

How do you read an NMR spectroscopy image?

Answer 39

Find the peaks, and use the table to determine the structure

Question 40

In NMR spectroscopy, when the charged nucleus generates a magnetic field and the protons are excited, if the nucleus is placed in an external field, how do the spinning protons act? (see slide 27)

Answer 40

The spinning protons act like bar magnetics. They twist so that they are parallel to the external field and can be in either direction (north or south)

Question 41

____ works by placing a sample in a strong magnetic field, which aligns the magnetic moments of certain atomic nuclei, like hydrogen. Radiofrequency pulses are then applied to excite these nuclei, causing them to "flip" to a higher state. When the nuclei relax back to their lower energy state, they emit electromagnetic signals at frequencies characteristic of their local chemical environment, which can be measured and analyzed to determine the molecule's structure

Answer 41

Nuclear magnetic resonance (NMR)

Question 42

Depending on their c____ e______, protons in a molecule are shielded by different amounts

Answer 42

Chemical environment

Question 43

In an NMR graph, what does the number of signals represent?

Answer 43

The number of signals shows how many different kinds of protons there are

Question 44

The _____ of the signals on an NMR graph shows how shielded or de-shielded the proton is

Answer 44

Location

Question 45

The ______ of the signal on an NMR graph shows the number of protons of that type

Answer 45

Intensity

Question 46

Signal _____ shows the number of protons on adjacent atoms

Answer 46

Splitting

Question 47

A measure of the difference in the resonance frequency of a nucleus relative to a standard reference compound (NMR values for chemical groups)

Answer 47

Chemical shift (delta)

Question 48

What does aromatic refer to in bonding?

Answer 48

Aromatic refers to a special kind of bonding in which the molecule has a cyclic or ringlike structure

Question 49

What does alkane refer to in bonding?

Answer 49

The bonds in an alkane are all single covalent bonds, specifically CC and CH

Question 50

GOODNOTES -> review the NMR spectra example on slide 33

Answer 50

completed

Question 51

Is NMR spectroscopy using in MRI medical imaging?

Answer 51

Yes!

Question 52

High energy electrons break molecules apart

Answer 52

Mass spectrometry

Question 53

What is mass spectrometry used to find?

Answer 53

Mass spectrometry is used to find the structure and molecular weight of the molecule

Question 54

Is mass spectrometry true spectroscopy?

Answer 54

No, because it's a destructive technique and it does not involve absorption or emission of light

Question 55

By varying the _____ ____ in mass spectrometry, ions of all masses are collected and counted

Answer 55

Magnetic field

Question 56

NMR spectra graphs use what as the x-axis?

Answer 56

Chemical shift (delta)

Question 57

In mass spectrometry graphs, what is used as the x-axis and what is used as the y-axis?

Answer 57

m/z (mass/charge) is on the x-axis and abundance is on the y-axis

Question 58

Describe how to read a mass spectrometry graph

Answer 58

Charge to mass ratio is shown, as well as abundances

Question 59

GOODNOTES -> complete the spectrometry and spectroscopy table on slide 39

Answer 59

completed

Question 60

Which step is NOT a part of a mass spectrometry experiment? ionization, crystallization, detection, mass analysis

Answer 60

Crystallization Ionization -> turning molecules into ions Mass analysis -> separating ions by their mass-to-charge ratio (m/z) Detection -> measuring the ions

Question 61

Technique for the separation, purification, and testing of compounds

Answer 61

Chromatography

Question 62

GOODNOTES -> outline the chromatography tree on slide 45

Answer 62

completed

Question 63

Which chromatography technique is this: utilizes the pressure-driven flow of a mobile phase through a column packed with a stationary phase to separate compounds in a chemical mixture

Answer 63

High performance liquid chromatography (HPLC)

Question 64

What are the axis labels for a HPLC (high performance liquid chromatography) chromatogram? (review slide 47)

Answer 64

RT (min) for x axis, and relative intensity for y-axis

Question 65

GOODNOTES -> draw the HPLC image in slide 46

Answer 65

completed

Question 66

What do normal phase and reverse phase chromatography do?

Answer 66

Normal phase uses a polar stationary phase and a non-polar mobile phase to separate compounds, with the most polar analytes eluting last Reverse phase uses a non-polar stationary phase and a polar mobile phase to separate compounds, with the most non-polar (hydrophobic) analytes eluting last

Question 67

Overall, they separate compounds based on their polarity by using stationary and mobile phases with opposite polarities

Answer 67

Normal phase and reverse phase chromatography

Question 68

Separates molecules by their surface charge, using a resin with fixed charges that interact with oppositely charged sample molecules

Answer 68

Ion exchange chromatography

Question 69

GOODNOTES -> draw the normal phase and reversed phase chromatography on slide 49

Answer 69

completed

Question 70

GOODNOTES -> draw the ion exchange chromatography example on slide 50

Answer 70

completed

Question 71

Powerful purification technique that separates biomolecules based on their specific binding to a ligand immobilized on a stationary phase

Answer 71

completed

Question 72

GOODNOTES -> draw the affinity chromatography example on slide 51

Answer 72

completed

Question 73

What are the two kinds of size exclusion chromatography?

Answer 73

Gel filtration chromatography and gel permeation chromatography

Question 74

Aqueous solvent (mobile phase) and hydrophilic beads (stationary phase)

Answer 74

Gel filtration chromatography

Question 75

Nonpolar organic solvent (mobile phase) and hydrophobic beads (stationary phase)

Answer 75

Gel permeation chromatography

Question 76

What is the main difference between gel permeation chromatography and gel filtration chromatography?

Answer 76

Gel filtration uses AQUEOUS solutions for separating biomolecules like proteins Gel permeation uses ORGANIC SOLVENTS for separating synthetic polymers

Question 77

Molecules are separated based on their size as they pass through porous beads

Answer 77

Size exclusion chromatography (SEC)

Question 78

Molecules larger than the average pore size are ______ from the pore

Answer 78

Excluded

Question 79

Molecular diameters that are significantly smaller than the pore can penetrate throughout the pore, so molecules with smaller diameters elute _____

Answer 79

LAST (SMALLER MOLECULES ELUTE LAST)

Question 80

GOODNOTES -> draw the example of the calibration curve for size exclusion chromatography

Answer 80

completed

Question 81

Why do all molecules elute in one band once they're beyond the permeation limit of the SEC calibration curve?

Answer 81

Because they can all freely and completely penetrate the pores

Question 82

Can a calibration curve for SEC be used to determine the MW and MN?

Answer 82

Yes~

Question 83

In a calibration curve for SEC, ____ ______ defines MW beyond which no retention occurs

Answer 83

Exclusion limit

Question 84

In SEC, larger molecules elute first because?

Answer 84

They cannot enter the pores of the stationary phase

Question 85

What does elute mean?

Answer 85

removing an adsorbed material using a solvent

Question 86

In SEC, smaller molecules elute later because?

Answer 86

They get trapped in the pores and take longer to come out

Question 87

Answer the iClicker on slide 54. Why did you choose your answer?

Answer 87

A is correct because larger molecules elute first

Question 88

Remember: in SEC, bigger = earlier

Answer 88

rememberrr

Question 89

GOODNOTES -> Draw explanation of size exclusion chromatography as shown here: https://docs.google.com/document/d/1IllAoLJAzGj3oa2AMjT8B46urtGAWJ36WeVIXiHiq-U/edit?tab=t.0

Answer 89

completed