2.2 Relative Mass Flashcards
What is the mass of a carbon-12 isotope?
12 atomic mass units (u)
What is the standard unit for atomic mass?
u - the mass of 1/12 of an atom of Carbon 12
What is relative atomic mass?
The weighted mean mass of an atom of an element compared to 1/12th the mass of a Carbon 12 atom
What does the weighted mean mass take into account?
The percentage abundance of each isotope
The relative isotopic mass of each isotope
What is relative isotopic mass?
The mass of an isotope compared to 1/12th the mass of a Carbon 12 atom
What happens in a mass spectrometer?
Sample is vaporised and ionised to form positive ions
Ions are accelerated (heavier ions move more slowly and are harder to deflect than lighter ions, so ions of isotopes are separated)
Ions are detected in a mass spectrum as a mass to charge ratio
Greater the abundance of an isotope, greater the signal
