Analytical Techniques Flashcards
What is mass spectrometry?
Chemists and physicists use a similar method for separating mixtures of substances into their components, turning them into beams of particles and then bending them withelectricityandmagnetismto make a kind of spectrum of differentatomsthat are easier to identify.
What are the 5 stages and technique of mass s?
A technique used to determine the specific identity and amount of atoms or molecules in a sample of material as well as determine the isotopic composition of an element (mass number and percent abundance).
A mass spectrometer separates and counts particles in five stages:
Vaporisation
Ionisation
Acceleration
Deflection
Detection
What is absorption spectroscopy?
Spectroscopy is the process of analysing light. A spectrometer is used to separate light into its component wavelengths which can be shone through a sample.
An atom in its ground state may gain energy as a result of:
Colliding with electrons – electric discharge
Electromagnetic radiation, such as light
Heat – collisions with particles of high kinetic energy
The energized electrons rise to different energy levels within the atom.
What is emission spectroscopy?
An atom whose electrons have absorbed energy is said to be in an excited state.
These excited electrons are unstable and after a very short time, they move back down to their original levels, releasing the same amount of energy previously absorbed.
The energy is emitted as photons of light.
What is hydrogen emission spectra?
This is the simplest spectra because hydrogen only has one electron.
Lyman series: ultraviolet region – transitions to lowest energy level.
Balmer series: visible region – transitions to second energy level.
Paschen series: infrared region – transitions to third energy level.
What is atomic absorption spectroscopy?
Analysing wavelengths that make up absorption/emission spectra is qualitative analysis – identity of sample is determined.
AAS is a modified version of absorption spectroscopy that can be used to perform quantitative analysis – finding an amount (quantity) of an element present.
It uses the principle of the Beer-Lambert Law: the concentration of the sample element is proportional to the amount of light absorbed.
AAS’s purpose is to measure the amount of light absorbed.
What is forming emission spectra?
The emitted light from a sample can be separated into individual wavelengths using a spectrometer.
The light is dispersed through a prism and shone onto a detector to produce an emission spectrum.
emission spectra of elements are the inverse of absorption spectra.
Scientists can determine the identity of elements in an unknown sample by comparing the lines in its emission spectrum to those known to be produced by specific elements.
