Atomic Spectroscopy Flashcards
What is “spectra”
Spectra arise from an interaction of energy with atoms or molecules once they have been GIVEN something that makes a change to them.
REV:
Atom = single neutral particle eg Hydrogen
Molecule = neutral particle made of two or more atoms bonded together Hydrogen and Oxygen
Ion = a group of atoms which bears a positive or negative charge
Cation = positively charged ion (more electrons than protons)
Anions - negatively charged ion (more protons than electrons)
Which type of spectrometer relies on electronic transition and what does it create in the molecules?
flame photometry - creates atomic emission
ultraviolet-visible, UV-Vis creates atomic absorption and molecular absorption
Which type of spectrometer relies on molecular vibration and what does it create?
Infrared creates stretching and bending of the molecule.
Which type of spectrometer relies on nuclear spin and what does it create?
Nuclear magnetic resonance (NMR)
Differences in analytical techniques….HIGH discriminators
Mass Spectrometry (fragmentation patterns and molecular weight)
Infrared spectroscopy
Raman spectroscopy (complimentary to Infrared spect - if it doesn’t pick up in infra then it will in raman)
Nuclear magnetic spectroscopy
X-Ray diffraction - the greatest discriminator
Differences in analytical techniques….MEDIUM discriminators
Capillary electrophoresis
Gas chromotography
Thin layer chromotography
Microcrystalline tests
Differences in analytical techniques….LOW discriminators
Colour tests
Flourescence spectroscopy
Melting point
UV spectroscopy
What is Atomic Spectroscopy?
A general method.
A high energy source (eg a flame or electric plasma) which can dissociate molecules into atoms.
Poofffffff….
The energy is absorbed and the atoms fall back toward the nucleus.
What is the order of longest length and lowest energy of the following waves?
UV, visible, radio, microwaves, gamma and x rays.
Gamma ray and x ray UV Visible Infrared Microwave and radio waves
Why is atomic spectroscopy widely used in forensics, biological, biomedical and environmental science?
Because it is useful for elemental analysis of metals and how much metal is present.
How does flame photometry work?
a type of absorption spectrometry
Sample dissovled in water and sprayed into flame.
Energy is removed as the solvent (water) evaporates.
The molecule breaks down into atoms.
The atoms become vapourised Poooofffff…..
The rest of the energy excites the electrons.
The expected wavelength is measured.
The absorbance is the amount of energy that has gone due to flame.
What is the Rydberg Equation?
This determines the wavelength of energy emitted during transition to the FINAL SHELL (n1) from the INITIAL SHELL (n2)
What is Planck’s Law?
Predicts the energy of photons emitted from a sample.
Measures the relationship between the energy travelling along the wave and the wavelength.
Amounts of energy for specific species are used for analysis.
Name some examples of use of flame spectroscopy and metals discovered…..
Blood serum
Na @ 589nm and K @ 766nm
Baby foods Ca @ 442nm
Blood serum in bipolar patients
Li @ 670nm
What is Beer Lambert Law?
Beer’s Law
Describes the relationship between the molar absorptivity and the specific absorbance of the compound being investigated.
