Analytical Techniques Flashcards
What is a mass spectrometry?
Mass spectrometry uses ionization to analyze molecules, determining molar mass, elements, functional groups, and isotopes. It is used for isotopic composition and organic structure analysis.
Which electron shells have the highest energy?
Further away shells have the most energy; while shells closest to the nucleus have lower energy.
What is the ground state of an electron?
The ground state of an electron is its lowest energy level (n=1) in a hydrogen atom, or the lowest available energy level shell in other atoms.
What is the excited state of an electron?
The excited state of an electron is when it absorbs energy and jumps to a higher energy level (shells).
What happens when an electron goes from its excited state back to ground state?
First, the electron loses all the extra energy and will return to its initial-low energy level. The energy is released as a photon (light) and the amount of energy released can be shown through colors.
What does the line spectra entail about the energy released by an electron?
Each color in the spectrum corresponds to light of a different energy, left is higher and right is lower energy released.
What is the absorption spectra?
It shows lines where energy in the form of light is being absorbed by an electron causing it to increase to a higher energy level.
What is the emission spectra?
When the excited electron loses its added energy and returns to its initial energy level (ground state), energy is emitted as light (photons) which have a certain wavelength (spikes).
What is the relation between the flame test and the absorption and emission spectrums?
The flame test identifies metal ions based on their unique flame colors, which result from electrons absorbing heat, jumping to a higher energy level, and releasing visible light when returning to the ground state.
What do the colours of the flames correspond to?
The colour and intensity of the flame aredetermined by the energy differences between the excited and ground states of these electrons, which vary from one element to another.
Deduce a limitation of using the flame test to identify different metal ions.
Cannot detect low concentration of most ions. If an ion is present in very small amounts, the emitted light may be too weak to see clearly, making it difficult to identify the metal.
What is an Atomic Absorption Spectroscopy (AAS)?
Atomic Absorption Spectroscopy (AAS) works on the same principle as the flame test but is more precise. The high temperature of the flame excites valence electrons to higher energy levels, and when they return to the ground state, they emit or absorb light at specific frequencies.
A hollow cathode lamp emits light of known wavelengths, which the vaporized sample absorbs. The amount of absorbed light is proportional to the metal ion concentration. The analyzer compares this absorbance to calibrated values to identify and quantify metals accurately.
How does an AAS Calibration curve work?
AAS uses a calibration curve to find metal ion concentration by comparing absorbance to known values. Higher absorbance means higher concentration, measured in mg/L or ppm. The curve ensures accuracy, with adjustments for dilution if needed.
