Chapter 12 - Forensic Spectroscopy

Question 1

Atomic Mass (weight)

Answer 1

• Mass of an atom that’s expressed in the standard unit of atomic mass units (amu)
• Equal to the # of protons and neutrons in the atom

Question 2

Atomic Mass Unit (amu)

Answer 2

• Atomic Mass Unit (AMU)
• Unit of mass that weighs 1/12 of the mass of a carbon-12 atom
• Used to express atomic and molecular weights

Question 3

Atomic Number

Answer 3

The # of protons in the nucleus of an atom

Question 4

Chromatography

Answer 4

• Process for separating components of a mixture
• Forensics: separating ink, blood, lipstick, etc

Question 5

Gas Chromatography

Answer 5

• Form of chromatography
• Separates mixtures into individual components
• Uses a gas as the mobile phase

Question 6

Half-Life

Answer 6

• Amount of time necessary for 1/2 of the original sample to change, decompose, or decay away

Question 7

Isotope

Answer 7

Atoms with the same # of protons but different #s of neutrons

Question 8

Mass Spectrometry

Answer 8

• Analytical method that separates molecules by their masses
• Measures mass to charge ratio
• Records mass distribution in mass spectrum

Question 9

Molecular Form

Answer 9

Defines the # of atoms of each element in one molecule of a compound

Question 10

Molecular Weight

Answer 10

• Mass of a molecule that is expressed in AMU
• Sum of the individual weights of atoms that make up the molecule

Question 11

Radioactivity

Answer 11

Spontaneous emission of particles/electromagnetic radiation in nuclear decay

Question 12

Radioactive Decay

Answer 12

Disintegration of unstable nuclei and emission of particles/electromagnetic radiation

Question 13

Radiocarbon Dating

Answer 13

• All living things absorb carbon. When they die, they stop absorbing it but the radioactive carbon that they’ve accumulated keeps decaying
• Can help determine the age of materials

Question 14

Retention/retardation Factor (Rf)

Answer 14

• Rf value is the ratio of the distance traveled by the substance to the distance traveled by the solvent front

Question 15

Spectroscopy

Answer 15

Study of the absorption and emission of light and other radiation by matter

Question 16

Stationary Phase

Answer 16

In chromatography, the component that doesn’t move during a separation

Question 17

Mobile Phase

Answer 17

The fluid (liquid or gas) that flows through a chromatography system (moving)

Question 18

Visible Light

Answer 18

• Electromagnetic radiation that can be detected by the human eye
• Between 280 nm to 750 nm

Question 19

Quantitative vs Qualitative Data

Answer 19

Quantitative - how many/much?; numbers/stats
Qualitative - answers “why?”; 5 senses; descriptive data

Question 20

Atomic Absorption

Answer 20

• Quantitative
• Technique for measuring the concentrations of metallic elements in materials

Analysis of blood samples, brain/muscle tissue, gunshot powder residue.

Question 21

Neuron Activation

Answer 21

• Qualitative & Quantitative
• Extremely sensitive technique used to find quantities of trace elements in a sample

Used to analyze inks and fibers

Question 22

Ultraviolet

Answer 22

• Quantitative
• Form of non-ionizing radiation that’s emitted by the sun and by artificial sources

Analyzes inks and fibers and can ID anything that appears colored

Question 23

Infrared

Answer 23

• Qualitative
• Used to ID small organic compounds

Used in alcohol analysis (breathalyzers), ID of unknown compounds, paint

Question 24

Mass Spectrometry

Answer 24

• Qualitative
• Can measure the mass-to-charge ratio of molecules present in a sample.

Used to ID drugs in and outside the body

Question 25

Gas Chromatography

Answer 25

- Qualitative & Quantitative - Used to separate/analyze compounds that can be vaporized without decomposition | Used to detect the presence/levels of poisons, toxins, drugs, chemical