Mass number, atomic number, and isotopes

Mass spectrometery

Measures relative atomic mass and frequency of different isotopes

The sample is vaporised and ionised

The ions are separated according to their charge and mass

Mass spectrometry steps

Samples of unknown substances are injected into a vacuum to be vaporised

They are then ionised into positive ions by firing electrons at them, electron impact ionisation

The positive ions are accelerated by an electric field. Lighter ions will accelerate greater

The ions drift with no electric field at the same speed they were travelling

Lighter ions hit the detector first than heavier ions. The ions gain an electron when they hit the detector, creating an electric current that can be detected

Mass spectrum is produced when the ions hit the detector

Relative atomic mass equation

relative abundance of each isotope x relative mass of each isotope

Total abundance

Relative atomic mass

The weighted average mass of an atom of en element with its naturally occurring isotopes compared to 1/12 the relative atomic mass of carbon 12

Relative isotopic mass

The mass of an individual atom of a particular isotope relative to 1/12 the relative atomic mass of carbon 12