Mass number and isotopes Flashcards
What is the definition of isotopes?
Atoms with the same number of protons with different numbers of electrons.
Name the 4 steps of Mass Spectrometry
Ionisation, acceleration, deflection, detection
Define the relative molecular mass
The average mass of the molecule on a scale where an atom of Carbon-12 is 12.
What is a mass spectrometer used for?
To measure the relative atomic mass, the isotopic abundance of an element and molecular structure of the samples being sent through the mass spectrometer.
What state must the samples be in before being sent through the mass spectrometer?
The elements must be turned into gas (through vaporisation).
How is the sample in the mass spectrometer ionised?
High energy electrons are fired at the particles which knock off electrons, forming positive ions.
What accelerates the ions in the mass spectrometer?
They’re accelerated by an electric field.
What deflects the ions in a mass spectrometer?
They’re deflected by a magnetic field.
Are heavier ions or lighter ions deflected by the magnetic field more?
Lighter ions are deflected more because they have more momentum.
How are ions detected in a mass spectrometer?
The strength of the magnetic field is slowly increased which means that different ions reach the detector. This produces a mass spectrum.
How is the relative atomic mass calculated?
The relative abundance of each isotope is multiplied by the mass/charge of each element, each individual calculation is added together from this and divided by the abundance of each isotope added together.
