1. Mass Spectrometry Main Concept:
An early model of the atom stated that all atoms of an element are identical. Mass spectrometry data demonstrate evidence that contradicts this early model.

2. Mass Spectrometry Mass Spectrometry How it works
How it changed our understanding of the atom
How we can use it

3. Mass Spectrometry

4. - A mass spectrometer (mass spec) ionizes and magnetizes a stream of particles
- Particles are sorted by mass
- The intensity of the different masses can help scientists to determine what elements are present; higher peaks = more element

5. - mass spec data provides evidence that early models of the atom (Dalton’s model) were incorrect
- new data requires modification the model
What’s going on here?
Chlorine
35.45 amu
Zirconium
91.22 amu

6. Br
79.90 amu
What’s going on here?
- Data from mass spectrometry also demonstrate direct evidence of different isotopes from the same element
- The average atomic mass can be estimated from mass spectra

7. Question:
What might the mass spectrometry data look like for boron which has two common isotopes boron-10 (about 90% found in nature) and boron-11 (about 10% found in nature)?