Mass spectrometry | Atomic structure and properties | AP Chemistry | Khan Academy

Explain that elements have different isotopes with varying atomic masses due to different neutron counts, and pose the question of how chemists distinguish between isotopes and determine their relative abundances in nature.

Heat a sample of zirconium to create free atoms, then bombard the atoms with an electron beam to ionize them by knocking out electrons and creating charged ions.

Use electric plates to accelerate the charged zirconium ions, propelling them rapidly through the instrument in preparation for magnetic separation.

Pass the accelerated ions through a strong magnetic field which bends their paths; lighter ions deflect more while heavier ions deflect less, separating isotopes by mass-to-charge ratio.

Collect ions at the detector where different isotopes strike at different locations; the number of ions detected at each position indicates the abundance of that isotope in the original sample.

Plot the detector data as a mass spectrum with atomic mass units on the horizontal axis and ion abundance on the vertical axis, showing the distribution of zirconium isotopes with masses 90, 91, 92, 94, and 96.

Explain that the horizontal axis may display either atomic mass or mass-to-charge ratio; when ions have different charges, the mass-to-charge ratio must be adjusted accordingly to determine true atomic mass.