INORGANIC ANALYSIS Chapter 6 Inorganic Compounds Compounds which

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INORGANIC ANALYSIS Chapter 6

INORGANIC ANALYSIS Chapter 6

Inorganic Compounds § Compounds which do not contain carbon § Metals- Tools, coins, weapons,

Inorganic Compounds § Compounds which do not contain carbon § Metals- Tools, coins, weapons, metal scrapings, paints, dyes, explosives, poisons

Trace Elements § Trace elements (<1%) - “invisible” markers, additional points of comparison §

Trace Elements § Trace elements (<1%) - “invisible” markers, additional points of comparison § Soil, fibers, glass, metallic objects, hair, paint

Atomic Structure § Nucleus- in the center, contains neutrons and § § § protons

Atomic Structure § Nucleus- in the center, contains neutrons and § § § protons Protons have a positive charge (1) Electrons have a negative charge (1/1837) Neutrons have a neutral charge (1)

Atomic Structure § Atomic number = the number of protons in the nucleus of

Atomic Structure § Atomic number = the number of protons in the nucleus of an atom, the number identifies the element (also tells the number of electrons) § Atomic mass (mass number) = the number of protons + the number of neutrons

Atomic Structure § Atoms that differ from other atoms of the same element by

Atomic Structure § Atoms that differ from other atoms of the same element by the number of neutrons in the nucleus (have the same number of protons and electrons) Ex: hydrogen has 3 isotopes – all have 1 proton but each has a different # of neutrons)

Atomic Structure § Electrons travel around the nucleus in orbital paths with § §

Atomic Structure § Electrons travel around the nucleus in orbital paths with § § § particular energy level Excited state- electrons pushed into higher orbitals (requires energy) Atomic Absorption Spectrophotometry- measures the value & amount of light energy going into atom Falls back after short period of time (releases energy) Emission Spectroscopy- collects & measures the various light energies given off E = hf : Energy difference between orbitals equals Planck’s Constant times frequency of light (absorbed or emitted)

Emission Spectroscopy § Emission Spectrum- light (energy) emitted from a § § § source

Emission Spectroscopy § Emission Spectrum- light (energy) emitted from a § § § source and passed through a prism is separated into its component colors or frequencies Continuous Spectrum- all colors merge to form continuous band (sunlight, incandescent) Line Spectrum- emitted as several individual colored lines representing definite wavelengths or frequencies (sodium lamp, mercury arc, neon) Vaporized, excited matter emits characteristic line spectrum (“fingerprint” of elements)

Emission Spectroscopy

Emission Spectroscopy

Emission Spectroscopy § Emission spectrograph- instrument which vaporizes, excites, (carbon electrode/ electrical arc) separates

Emission Spectroscopy § Emission spectrograph- instrument which vaporizes, excites, (carbon electrode/ electrical arc) separates frequencies and records the line spectra of elements

ICP § Inductively Coupled Plasma Emission Spectrometry § Identifies and measures elements through light

ICP § Inductively Coupled Plasma Emission Spectrometry § Identifies and measures elements through light energy emitted by excited atoms using hot plasma torch (argon gas) § Radio- Frequency (RF) coil carries current § Accepted method of identification and characterization of mutilated bullets and glass fragments

Atomic Absorption Spectrophotometer § Light (energy) absorption of element (photon of § § §

Atomic Absorption Spectrophotometer § Light (energy) absorption of element (photon of § § § light interacts w/ an electron jumps to higher orbital) Higher conc. of element more light absorbed Quantitative (even trace elements) Determine one element at a time Graphite furnace or heated strip of metal increases efficiency and sensitivity (one-trillionth of gram) Simple, low cost

Neutron Activation Analysis § § § Nuclear energychanging number of subatomic particles Radioactivity- emission

Neutron Activation Analysis § § § Nuclear energychanging number of subatomic particles Radioactivity- emission of radiation when unstable nuclei spontaneously disintegrate (radioactive decay) Ex- radium, uranium, thorium

Radioactivity § Three types of radiation: 1)Alpha rays- positively charged helium atoms minus orbiting

Radioactivity § Three types of radiation: 1)Alpha rays- positively charged helium atoms minus orbiting electrons 2)Beta rays- electrons 3)Gamma rays-high energy form of electromagnetic radiation (*)

Radioactivity

Radioactivity

Neutron Activation Analysis § Nondestructive method for identifying and quantitating trace elements § Bombards

Neutron Activation Analysis § Nondestructive method for identifying and quantitating trace elements § Bombards w/neutrons, measures emitted gamma rays § Extremely sensitive (nanogram) § Simultaneous analysis for 20 -30 elements § Very expensive (nuclear reactor + analyzer) § Metals, drugs, paint, soil, GSR, hair

JFK Assassination § 1963, Lee Harvey Oswald, Warren Commission § 3 shots from Texas

JFK Assassination § 1963, Lee Harvey Oswald, Warren Commission § 3 shots from Texas School Book Depository behind JFK § JFK hit by 2 bullets 1: back throat Gov. Connally back chest right wrist left thigh 2: JFK’s skull (fatal)

JKF Assassination § Evidence in depository: * 6. 5 -mm military rifle w/Oswald’s palm

JKF Assassination § Evidence in depository: * 6. 5 -mm military rifle w/Oswald’s palm print * 3 spent 6. 5 mm cartridge cases * Oswald seen in AM and minutes after shooting * “Grassy knoll”?

JFK Assassination § 1977 - Bullet, fragments and wounds examined for trace elements §

JFK Assassination § 1977 - Bullet, fragments and wounds examined for trace elements § Western Cartridge Co. /Mannlicher. Carcano bullets contain antimony & silver § Neutron Activation Analysis § Stretcher and wrist bullet indistinguishable § Car and brain fragments indistinguishable § Results consistent with findings § See Table 6 -3 pg. 153

X-Ray Diffraction § Identifies crystalline materials, how elements are combined into compounds § Solid,

X-Ray Diffraction § Identifies crystalline materials, how elements are combined into compounds § Solid, crystalline materials: definite, orderly arrangement of atoms § 95% of inorganic compounds § Diffraction pattern formed by reflection of X -rays (“fingerprint”) § Not sensitive (<5 % of mixture) § Ex- Explosives

X-ray Diffraction

X-ray Diffraction