Purpose Most textbooks mention mass spectrometry when dealing with the topic of atomic isotopes. Some have pictures of the instrument and many include a sample of a spectrum for one element. The purpose of this activity is to provide students with more than one example, which they have acquired in a "hands-on" fashion. Ideally, upon completion of this activity, the student will have a better idea of how scientists determine isotopic abundances and how those are related to the "natural" atomic weight of an element. This activity can meet several MSDE Core Learning Goals . Prior Knowledge Before this activity, students have reviewed the structure of the atom and some of the historical experiments which led to the current threories of this structure. In addition, students have worked with a program on a graphing calculator which simulates the behavior of a single ion within a mass spectrometer. In that simulation, the students look for the approriate magnetic field strength which will allow an ion to pass through a set of parallel plates and then follow a curved path to a detector. Worksheet for Mass Spec Activity Program Listing for MATLab program and sample graph Sample data file Time and Evaluation of Activity Students were able to complete the worksheet in about 45 minutes. That included my requirement that they sketch each plot and use ginput to determine the actual values of the peaks. The students evaluated the worksheet and seemed to have no trouble using it. In later class discussions and book work, several students have referred back to this activity to clarify their understanding. MSDE CORE Learning Goals Goal 1: Skills and Processes Expectation 4: The student will demonstrate that data analysis is a vital aspect of the process of scientific inquiry and communication Indicator 6: The student will use spreadsheet, graphing, and database programs and probeware on computers and/or graphing calculators Indicator 8: The student will use models and computer simulations to represent systems Expectation 5: The student will use appropriate methods for communicating in writing and orally the processses and results of scientific investigation Indicator 1: The student will demonstrate the ability to summarize scientific concepts, processes and data through written communications Indicator 5: The student will use computers and/or graphing calculators to produce tables, graphs and spreadsheet calculations Expectation 6: The student will use mathematical processes. Indicator 1: The student will use ratio and proportion in appropriate situations to solve problems Indicator 3: The student will manipulate quantities and/or numerical values in algebraic equations Indicator 4: The student will judge the reasonableness of an answer Goal 4: Concepts of Chemistry Expectation 2: The student will explain that all matter has structure and the structure serves as a basis for the properties of and the changes in matter.

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