Ch. 9 Inorganic Analysis: Forensic Determination of Metals and Gunshot Residue

Question 1

atomic absorption spectrophotometry (AAS)

Answer 1

a quantitative analysis technique that measures absorption of light by vaporized elements in a sample

Question 2

atomic mass unit

Answer 2

the sum of the number of protons and the number of neutrons in the nucleus of an atom

Question 3

atomic number

Answer 3

the number of protons in the nucleus of an atom of an element

Question 4

compound

Answer 4

a substance formed by the chemical combination of two or more elements in fixed proportions

Question 5

continuous spectrum

Answer 5

a pattern in which one color of light merges into the next color that is produced when white light is passed through a prism

Question 6

electromagnetic radiation (EMR)

Answer 6

a general term the is used to describe energy that is encountered daily

Question 7

electron

Answer 7

a subatomic particle with a negative charge of one (-1) and negligible mass

Question 8

element

Answer 8

a fundamental building block of matter that cannot be decomposed into a simpler substance by ordinary chemical means

Question 9

energy-dispersive x-ray

Answer 9

a technique that measures the energy of X-rays emitted in the scanning electron microscope

Question 10

energy level

Answer 10

any several regions surrounding the nucleus of an atom in which the electrons move

Question 11

excited state

Answer 11

the state of an atom in which an electron has acquired energy to move to a higher energy level

Question 12

frequency

Answer 12

the number of crests that pass a fixed point in 1 sec

- 1Hz = frequency of 1 cycle (passage of 1 complete wave) per second

Question 13

ground state

Answer 13

the state of an atom in which all of its electrons are their lowest possible energy levels

Question 14

group

Answer 14

one of the vertical columns of elements in the periodic table

Question 15

gunshot residue (GSR)

Answer 15

material discharged from a firearm other than the bullet

Question 16

inductively coupled plasma (ICP)

Answer 16

a high-energy argon plasma that uses radio-frequency energy

Question 17

line spectrum

Answer 17

a spectrum produced by an element that appears as a series of bright lines at specific wavelengths, separated by dark bands

Question 18

metals

Answer 18

malleable elements

• lustrous
• good conductors of heat & electricity
• tend to lose electrons to form positively charged ions

Question 19

modified Greiss test

Answer 19

a test for the presence of nitrites in gunshot residue

Question 20

molecule

Answer 20

the smallest unit of a compound that retains the characteristics of that compound

Question 21

neutron

Answer 21

an electrically neutral subatomic particle found in the nuclei of atoms

Question 22

neutron activation analysis (NAA)

Answer 22

an analysis method that bombards the sample with neutrons and then measures the isotopes produced

Question 23

nonmetals

Answer 23

elements that lack the properties of metals

Question 24

nucleus

Answer 24

the small, dense, positively charged central core of an atom

- composed of protons & neutrons

Question 25

orbital

Answer 25

the sublevels of principal energy levels (s, p, d & f)

Question 26

period

Answer 26

one of the horizontal rows of elements in the periodic table

Question 27

periodic table

Answer 27

the elements arranged in order of atomic number | - each element has a unique atomic number

Question 28

plasma

Answer 28

a high temperature gas that has a portion of its atoms ionized which makes the gas capable of conducting electricity

Question 29

principal energy level

Answer 29

one of the energy levels to which electrons are limited

Question 30

proton

Answer 30

a subatomic particle with a relative positive charge of (+1) and a mass of 1 - a hydrogen ion

Question 31

quantum

Answer 31

the smallest increment of radiant energy that may be absorbed or emitted

Question 32

scanning electron microscopy with energy-dispersive X-ray (SEM-EDX)

Answer 32

the preferred method for the detection of GSR | - investigator applies an adhesive tape directly to the suspect's hands (or other surface) to lift the GSR

Question 33

semimetal (metalloid)

Answer 33

elements with properties that lie between those of metals and nonmetals

Question 34

wavelength

Answer 34

the distance between adjacent wave crests | - usually measured in nanometers (nm)

Question 35

X-ray fluorescence spectrometry (XRF)

Answer 35

a technique that measures the emission of an x-ray when a sample is exposed to higher-energy X-rays - energy of the emitted X-ray indicates which element released it

Question 36

The building blocks from which all matter is constructed are called _______.

Answer 36

atoms

Question 37

Substances that are composed of 2 or more elements are called _______.

Answer 37

compound

Question 38

The number of naturally occurring elements is ________.

Answer 38

98

Question 39

A molecule is a combination of _________ or more elements.

Answer 39

2

Question 40

A proton has a(n) ________ charge.

Answer 40

positive

Question 41

The nucleus of an atom is composed of ________ and ________.

Answer 41

protons & neutrons

Question 42

The atomic number indicates the number of _________ in the nucleus.

Answer 42

protons

Question 43

In a neutral atom, the number of protons is equal to the number of _________.

Answer 43

neutrons

Question 44

The periodic table is divided into 18 vertical columns called _______.

Answer 44

groups

Question 45

Elements within a group on the periodic table have similar _______ properties.

Answer 45

physical & chemical

Question 46

The elements that are good conductors of electricity and heat and have a shiny appearance are called _______.

Answer 46

metals

Question 47

Elements that do not conduct heat or electricity are called ________.

Answer 47

nonmetals

Question 48

White light from an incandescent light bulb, when passed through a prism, produces a(n) ________ spectrum.

Answer 48

continuous

Question 49

An element that is placed in a flame emits light that, when passed through a prism, produces a(n) _________ spectrum.

Answer 49

line

Question 50

The alkali metals (Group 1A) all have ________ electron(s) in their outermost energy levels.

Answer 50

1

Question 51

The halogens (Group VIIA) all have ________ electron(s) in their outermost energy levels.

Answer 51

7

Question 52

The three metals most commonly used for fabricating everyday objects are _______, _________, and _______.

Answer 52

iron aluminum copper

Question 53

________ are mixtures of metals that are created to have properties that are more desirable than those of their components.

Answer 53

alloys

Question 54

Glass is composed mostly of the elements _______ and _______.

Answer 54

--

Question 55

A(n) _________ is a mixture of gases that conduct electricity.

Answer 55

--

Question 56

The X-ray beam of the XRF strikes a(n) ________-shell electron, which causes it to be ejected.

Answer 56

--

Question 57

The XRF measures the composition of the _________ of the sample.

Answer 57

--

Question 58

Collecting GSR for AAS analysis involves the use of swabs containing ________ that are rubbed on the skin of the head.

Answer 58

--

Question 59

The atomic absorption spectrometer uses a(n) _______ furnace to vaporize the collected GSR.

Answer 59

--

Question 60

The collection of gunshot residue for the scanning electron microscope analysis uses a(n) _______ ________ to pick the GSR from the skin.

Answer 60

--

Question 61

A scanning electron microscope operates on the same principle as the light microscope but uses ________ rather than light to illuminate the sample.

Answer 61

--

Question 62

In SEM, some of the electrons striking the surface cause _________ to be emitted.

Answer 62

--

Question 63

By measuring the energy of the X-rays emitted in SEM, the identity and amount of each ________ on the GSR can be determined.

Answer 63

--

Question 64

The incomplete combustion of gunpowder releases a nonmetal ________.

Answer 64

nitrile (NO2)