Intro To Criminalistics - Ch. 4 And 5

Front 1

2 Forms of Matter?

Back 1

Crystalline and amorphous (sugar vs. flour)

Front 2

What is a Crystalline solid?

Back 2

specific forms that represent various geometric shapes (cube, octahedron, etc.)

Front 3

What is a chemical property?

Back 3

have to do with the reactivity of substances

Front 4

What is a physical property?

Back 4

describe a substance within its own context – things like color, weight, melting point, density

Front 5

What is the standard measurement of weight?

Back 5

grams (454 g = 1 lb)

Front 6

1000 grams =

Back 6

1 kilogram

Front 7

What is the stadard measurement of volume?

Back 7

liter (approximately 1 quart)

Front 8

1 cc =

Back 8

1 milliliter (ml) = 20 drops

Front 9

What is the stadard measurement of length?

Back 9

Meter (approximately 39 inches)

Front 10

Nanometer (nm) =

Back 10

1/1,000,000,000 Meter

Front 11

Millimeter (mm) =

Back 11

1/1000 Meter (m)

Front 12

Centimeter (cm) =

Back 12

1/100 Meter

Front 13

What is mass?

Back 13

the quantity of matter (1 inch square of lead versus 1 inch square of cork)

Front 14

What is density?

Back 14

mass per unit volume

Front 15

What is specific gravity?

Back 15

mass as compared to an equal mass of water (what does a value of less than 1 mean? Greater than 1?) - cork vs. lead

Front 16

What is weight?

Back 16

the result of gravity : wt. on earth vs. on moon

Front 17

What is temperature?

Back 17

A measure of heat energy

Front 18

Fahrenheit

Back 18

b.p. of water is 212, f.p. is 32
F = 9/5 C + 32

Front 19

Celsius

Back 19

b.p. of water is 100, f.p. is 0

C = 5/9 (F-32)

Front 20

Kelvin

Back 20

all atomic motion ceases at -273 C (0 K); K = C + 273

Front 21

What is light?

Back 21

has the properties of both matter and energy

Front 22

How does light travel?

Back 22

as a wave

Front 23

Visible light consists of a combination of different ____________ of light

Back 23

wavelengths

Front 24

Each different wavelength exhibits a color known as

Back 24

dispersion

Front 25

The combination of all the colors (red, orange, yellow, green, blue and violet) appears as _______ light

Back 25

white

Front 26

What is dispersion?

Back 26

variation of RI with wavelength

Front 27

What is the refractive index?

Back 27

bending of light

Front 28

What is a Refractometer?

Back 28

A high resolution optical sensor measures the total reflection of a light beam emitted by a special LED light source after hitting the sample. This total reflection is converted into refractive index

Front 29

Visible light consists of only a very _______ portion of the entire electromagnetic spectrum

Back 29

narrow

Front 30

A color of visible light includes a ______ of wavelengths (a band)

Back 30

number

Front 31

What is a wavelength?

Back 31

crest to crest distance (in nanometers – 1 x 10‾9)

Front 32

The shorther the wavelength the ________ the energy.

Back 32

greater

Front 33

What is Isotropic?

Back 33

only one RI value no matter the orientation in polarized light (cubic xtals, glass)

Front 34

Anisotropic (birefringent)

Back 34

RI varies with orientation in polarized light (non-cubic xtals, fibers, polymers)

Front 35

When light reflects off nonmetallic surfaces such as glass, water, or a road surface, the light is polarized. The reflected light consists of waves which are vibrating in a direction ____________ (parallel, perpendicular) to the reflecting surface.

Back 35

parallel

Front 36

Spectroscopy

Back 36

the measurement of the absorbance of electromagnetic radiation (light) – primarily UV & IR (only limited use of visible in criminalistics)

Front 37

UV spectroscopy

Back 37

involves electronic excitation

Front 38

IR spectroscopy

Back 38

involves molecular bending, & stretching (no electronic transition)

Front 39

Soil collection protecol?

Back 39

Paper or cloth containers, Knives, trowels, brushes or spatulas

Front 40

Soil testing protocol?

Back 40

Color; Moisture content (how would you test it?); pH (what is it? How is it tested?); Ash content; Particle size; Density gradient; (bromoform/bromobenzene); Microscopy (light, fluorescence, dispersion staining)

Front 41

What is an intensive property?

Back 41

a property of matter that is the same regardless of the size of the substance (i.e. density)

Front 42

What is refraction?

Back 42

the bending of a light wave as it passes from one medium to another.

Front 43

What is the RI?

Back 43

The ratio of the speed of light in a vacuum to its speed in a given substance. (Intensive property)

Front 44

What is an amporphous solid?

Back 44

A solid in which the constituent atoms or molecules are arranged in random or disordered positions.

Front 45

What is glass?

Back 45

A super cooled liquid; sand and metal oxides

Front 46

What is tempered glass and where is it found?

Back 46

Glass that is strengthened by rapid heating and cooling of the glass surface; required in automobile rear and side windows.

Front 47

What kind of glass fractures to tempered glass make?

Back 47

mosaic patter with no sharp edges

Front 48

What is laminated glass and where is it found?

Back 48

Two sheets of ordinary glass bonded together with a plastic in between; Required in the windshields of cars.

Front 49

What is Plate (Floating) Glass and where is it found?

Back 49

Molten glass that is found in store windows.

Front 50

The physical properties of ________ and _________ _______ are most widely used for characterizing glass particles.

Back 50

density; refractive index (class characteristics)

Front 51

What is a radial fracture?

Back 51

A crack in a glass that extends outward like the spoke of a wheel from the point at which the glass was struck (Ray goes away)

Front 52

What is a concentric fracture?

Back 52

A crack in the glass that forms a rough circle around the point of impact (Con comes to)

Front 53

What are Wallner lines (as associated with glass fractures)?

Back 53

fracture lines on the edges of radial & concentric fractures

Front 54

Which direction do Wallner lines flow towards on radial fracture edges of glass with regard to the force that produces them?

Back 54

away from

Front 55

How was the Sink-Float method used in one of your lab exercises

Back 55

To compare glass densities

Front 56

Where would you find beveling on glass fractures?

Back 56

beveled margin is the exit side

Front 57

Given the fact that most crystalline solids are anisotropic and that glass is one of the few isotopic substances that a criminalist routinely encounters, how could these differences be used in non-destructive testing to distinguish glass particles from, say, quartz or calcite?

Back 57

wxamine them with a polarizing microscope; the glass cannot be seen between crossed polars but the anisotropic particles like quartz will be visible at certain orientations.

Front 58

Under what possible circumstance could a glass fragment be identified as having come from the same exact source as another glass fragment?

Back 58

When there is a physical match made (i.e. jig-saw puzzle fit)

Front 59

List 2 class characteristics of glass

Back 59

thickness, color, melting point, specific gravity, elemental composition, surface texture

Front 60

What is the value of soil evidence?

Back 60

The real significance depends on the frequency of occurrence of similar soil

Front 61

How could you measure the moisture content in a soil sample?

Back 61

Use a scale and an oven

Front 62

What analytical technique permits the elemental composition of the minerals in a soil sample to be determined?

Back 62

Inductively coupled plasma emission spectroscopy (ICP)

Front 63

Why is “breathable” packaging most important for soil evidence samples?

Back 63

so the organic portion does not decompose at an increased rate

Front 64

In the determination of the quantity of organic material in a soil sample consisting of both organic and inorganic components, the most meaningful results would be obtained by

Back 64

Weigh it then heat it to high temperature to burn off the organic fraction and re-weigh it

Front 65

What is a density-gradient tube?

Back 65

A glass tube filled from bottom to top with liquids of successively lighter denisities; used to determine the density of soil.

Front 66

What test should be done on soil?

Back 66

Moisture content; pH; Ash content; particle size; density gradient; microscopy.

Front 67

How should standard/reference soil samples be collected?

Back 67

vrious intervals within a 100-yard radius of the crime scene; site of the cirme; all possible alibi locations
Only the op layer of soil

Front 68

How should soil samples be packaged?

Back 68

Individual plastic vials; each vial should be marked to indicate the location of the sample; Soil on suspect carefully preserved - if on object it must not be removed.

Front 69

Matter

Back 69

All things of substance. composed of atoms and molecules

Front 70

Element

Back 70

Fundamental particle of matter. An element cannot be broken down into simpler substance by chemical means.

Front 71

Periodic Table

Back 71

A chart of elements arranged in a systematic fashion.

Front 72

How many naturally occurring elements are there?

Back 72

89

Front 73

atom

Back 73

The smallest particle of an element that can exist and stil retain its identity as that element

Front 74

Compounds

Back 74

A pure substaance composed of two or more elements

Front 75

Physical State

Back 75

A condition or stage in the form of matter; solid, liquid, gas

Front 76

Solid

Back 76

State of mattter in which the molecules ar held closely together in a rigid state

Front 77

Liquid

Back 77

State of mattter in which molecules are in contact with one another but are not rigidly held in place; occupies specific volume

Front 78

Gas (Vapor)

Back 78

State of matter in which the attractive forces betwen molecules are small enough to permit the to move with complete freedom; no definite shape or volume

Front 79

Sublimation

Back 79

A physical change from the solid state directly into the gas state (solid CO2 - dry ice)

Front 80

Physical Change

Back 80

Changes in physical state; no new chemical species formed

Front 81

Phase

Back 81

A uniform body of matter

Front 82

Immiscible liquids

Back 82

Difference in phases that are not dissolved in each other; Oil and Water - Oil is non-polar and Water is polar

Front 83

Organic Substance

Back 83

substances that contain carbon

Front 84

Inorganic Substances

Back 84

All other known chemical substances

Front 85

Spectrophotometry

Back 85

Identifying organic substances by their absorptions of different wavelengths of light; must be pure specimen

Front 86

Chromatography

Back 86

Means of seperating and tentatively identifying the components of a mixture. Ex. illicit drugs

Front 87

Henry's Law

Back 87

At a given temperature, the ratio of vapor in air to vapor in liquid for a volatile substance dissolved in liquid will be constant in a closed system.

Front 88

Gas Chromatography

Back 88

seperates mixtures on the basis of their distribution between a stationary liquid phase and a moving gas phase

Front 89

Pyrolysis Gas Chromatography

Back 89

Some solids which can not be dissolved in a solvent for GC - paint chips, fibers, plastics - heated or pyrolyzed to high temps (absence of O2) so they will decompose into gas - gives fingerprint

Front 90

HPLC: High Pressure Liquid Chromatography

Back 90

Moving phase is liquid pumped through column with small particles treated with a chemical; sample introduced and different components are attracted to different degrees of particles; takes place at room temp; useful for explosive analysis and heat senstive drugs (LSD)

Front 91

Thin-Layer Chromatography

Back 91

glass plate coated with silicia gel; sample dissolved in volatile solvent; spotted on TLC plate; plate is set into tank with liquid in bottom; liquid moves up plate by capillary action; places under UV light and materials will fluoresce; no absolute identification

Front 92

Electrophoresis

Back 92

Used gel coated plate as stationary phase; electrical potential is used for mobile phase; useful for seperation of enzymes (DNA and proteins)

Front 93

Visible Light

Back 93

Colored light ranging from red to violet in the electromagnetic spectrum

Front 94

Frequency

Back 94

The number of waves that pass a given point per second

Front 95

What general type analysis did the crime lab likely use to identify the residue as being consistent with coming from ammunition primer?

Back 95

Inorganic

Front 96

What do mass spectrometry (MS) and infrared spectroscopy (IR) allow that techniques like gas chromatography (GC) and ultraviolet spectroscopy (UV) do not?

Back 96

Positive molecular identification

Front 97

The reason that ultraviolet spectroscopy (UV) results in spectra that are sometimes pretty similar for many different compounds is that

Back 97

The absorption of ultraviolet energy by the electrons in atoms is quantitatively and qualitatively similar in many different compounds

Front 98

Which electromagnetic radiation has the highest energy?

Back 98

Gamma

Front 99

Which electormagnetic radiation has the shortes wavelength?

Back 99

Gamma

Front 100

Which one of the following techniques is best suited to the analysis of the inorganic components of paint samples?

Back 100

ICP/MS

Front 101

Which type of action (electronic transition or molecular bond bending, stretching and/or vibrating) is caused by UV and which by IR?

Back 101

UV causes electronic transitions; IR causes bond bending, etc

Front 102

What is an example of an organic compound frequently analyzed by crime labs?

Back 102

cocaine

Front 103

What is polarized light?

Back 103

light that is vibrating in only one plane; Ex: Light reflected off a roadway

Front 104

What analytical problem is most frequently associated with street drug samples?

Back 104

They are not pure

Front 105

Which technique has greater specificity, IR or UV spectrophotometry?

Back 105

IR

Front 106

An example of an inorganic substance that a criminalist would be likely to analyze

Back 106

the metallic portion of paint

Front 107

Pyrolysis GC is a technique used to analyze polymers. Why is the technique somewhat unsuitable as the method of choice in many trace evidence cases?

Back 107

It is destructive, so the entire sample may be consumed

Front 108

If a beam of light strikes a piece of glass at exactly 90 degrees rather than at an acute angle like 60 degrees, what happens to the light upon entering the glass?

Back 108

it is slowed down

Front 109

The criminalist is asked to analyze a street drug sample of unknown composition. What instrumental technique would provide the fastest and most definitive results as to its composition?

Back 109

GC/MS

Front 110

What instrument does a criminalist use to distinguish between different colors for paint specimens or fibers?

Back 110

Microspectrophotometer

Front 111

What is the electromagnectic spectrum?

Back 111

large family of radiation waves

Front 112

What is a laser?

Back 112

light amplification by the stimulated emission of radiation beam; light that has all waves pulsating in unison

Front 113

What are the parts of a spectrophotometer?

Back 113

Source, slit/prism; sample holder; detector; recorder

Front 114

UV Spectroophotometry

Back 114

Measure the absorbance of UV and visible light as a function of wavelength or frequency; tool for probable identity

Front 115

IR Spectrophotometry

Back 115

measures absorption of infrared shor frequencies of lighe before red in the visible spectrum; distinctive - "fingerprint" of substance

Front 116

Mass Spectropmetry

Back 116

Usually coupled with GC; the unique feature of mass spec. is that under controlled conditions no two substances produces the same fragmentation pattern - "fingerprint"