Mass Spectrometer Model

Mass Spectrometer Model

"What are we doing to help kids achieve?"

My students just finished an activity about . Each year there is always one or more student who ask about the mass of isotopes. How do scientists solve for that mass experimentally?

One way scientists do this is by using a mass spectrometer. Mass spectrometers first form atoms into ions and then pass them through magnetic fields. Atoms of different masses respond differently to the magnetic field. Flinn Scientific has a nice of this. It is simply a piece of plexiglass with a magnet underneath. The "atoms" are metal spheres rolled down a ramp. The magnet effects the spheres differently based on their masses. I have used this model but with a twist suggested by Irwin Talesnick. Irwin does a similar experiment but with one added feature. The plexiglass is coated with paper and the students do not know the magnet is present. They must predict what will happen. The first "atom" is a large billard ball and it goes straight.The next "atom" is as large as the billiard ball but is metallic, which represents the "ion" idea. Subsequent "isotopes" are deflected more or less based on their mass. This is similar to an actual mass spectrometer. Students usually have an "aha" moment when the second "atom" is deflected and then they quickly want to look underneath the plexiglass.

Mass Spectrometer Model

 

I have been doing this for several years. It always seems to get a nice reaction from students. They want to explore the idea more and it generates questions. It also costs much less than an actual spectrometer.....

Do you have a great quick demonstration? Would love to see it...don't be afraid to share...

Community: 

NGSS

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds.

Summary:

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. Use a model to predict the relationships between systems or between components of a system.

Assessment Boundary:
Clarification:

Students that demonstrate understanding can develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.

*More information about all DCI for HS-PS1 can be found at  and further resources at .

Summary:

Students that demonstrate understanding can develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.

Assessment Boundary:

Assessment does not include quantitative calculation of energy released. Assessment is limited to alpha, beta, and gamma radioactive decays.

Clarification:

Emphasis is on simple qualitative models, such as pictures or diagrams, and on the scale of energy released in nuclear processes relative to other kinds of transformations.