chemistry manipulatives for middle school students

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Chemistry Manipulativesfor Middle School Students

Lynn A. MeltonUniversity of Texas at Dallas

[email protected] CAST November 6, 2008

mailto:[email protected]

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Website

• http://www.chemchapterzero.com

• The concepts are presented in greater detail.

• PowerPoint presentations can be downloaded.

http://www.chemchapterzero.com/

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Fundamental Concepts ofChemistry

• Atoms

• Bonding/Molecules/Reactions

• Structure/Properties– Activity of molecule derives from its structure

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Atoms: Key Question• If a sassy eighth grader asked you “So why

– other than you and the book say so – should I accept that every material in the world is made up of atoms? After all, I cannot see atoms.”

• Your answer ….

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Atoms: Key Question

• Your answer ….– Define an atom carefully– Data #1:Atomic Force Microscopy (the world is granular)– Data #2: Mass Spectrometry

(the particles have different weights)– Work on “Seeing Without Seeing”

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Atoms

• Definition of an atom (a la Melton)– Rip any piece of the world apart, but you may

use only the energies available to the ancients – horses, flames, and lightning. When you cannot rip the smaller pieces apart any longer [to produce only neutral particles] then those last [neutral] particles are ATOMS.

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AtomsDigression

• Words that may come up. (If they don’t ask, don’t bring them up; Keep to the simple model)– Electron, proton, neutron: subatomic particles, they will

be discussed as more complex MODELS– Element: a group of atoms all of which have the same

number of protons– Ion: a atom in which the number of electrons is not the

same as the number of protons– Isotopes: atoms that have the same number of protons

but different numbers of neutrons

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Atoms: The Concept

• The weight of anything in the world is the same, regardless of how finely you divide it.

• Or, when you add up the weight of all the pieces, you get the weight of the original thing.

• The world is granular; it is– Sand rather than shampoo

– Grapes rather than jello

• Every material in the world is built from atoms.

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Let’s Work with Atoms

• This hands-on exercise is part of a series of lessons, all designed to help students accept that atoms are real.

• Since, atoms are too small for us to see with our eyes, let’s work on Seeing Without Seeing.

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AtomsSeeing Without Seeing

• What do we need to know about atoms?– What is your weight?– What can I build with you? (or, What other

atoms can you bond to?)

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• Each team must have an A and a B– A is the person with the gaudiest clothing

• In this exercise, A is the “doer” and B is the “recorder”.– A may not write– B may not touch.

• We will switch roles later.

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• A space probe has just returned from Planet Xanadu with samples of material.

• Your assignment is to go into the laboratory and find out whether the samples display the same chemistry that we observe on earth.

• In particular, on Planet Xanadu, is there a periodic table?

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• The garbage bag is your laboratory. It contains material from Planet Xanadu.

• One person inserts both hands into the garbage bag and does the research. The other person records the results.

• Please do not peek. At the right time, I will tell you when to look.

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• Carry out your research, write up the results, and make sure that A and B agree on what has been written.

• Switch bags with adjacent team.

• Check the results of the other team, but now A is the “recorder” and B is the “doer”.

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• Now, the whole group discusses their results.

• This is our version of an international scientific meeting.

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• Hands On Time!

• Go to it!

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• Switch bags with another team.

• Each team analyzes the other sample.

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• Now, all together, let’s discuss the results.

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• On Planet Xanadu, is there a periodic table?

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• Now, look at the atoms.

• What do we see with our eyes?• Why are the atoms made the way they are?

– Color?– Shape?– Weight?– Bonding?

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AtomsWhat data do we have?

• Atomic Force Microscopy– A very sensitive probe is scanned across the

surface, and the force on the probe is measured– By using electronics to keep the force constant,

we can – line by line – generate a profile of the surface

– The best instruments can “feel” individual atoms.

– Conclusion: the world is granular.

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AtomsWhat data do we have?

• Atomic Force Microscopy (neat websites)• http://www.mee-inc.com/afm.html • http://www.rhk-tech.com/hall/NaCl-mica.html • http://stm2.nrl.navy.mil/how-afm/how-afm.html • http://www.omicron.de/index2.html?/results/

atomic_resolution_on_si_111_7x7_in_non_contact_mode_afm/~Omicron

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AtomsWhat AFM data do we have?

Silicon surface

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NaCl (salt) surface

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• Conclusion:

– The world “feels” granular.

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AtomsWhat MS data do we have?

• Mass Spectrometry separates atoms (actually ions) according to their differing masses.

• Different masses have different trajectories!

• Real mass spectrometers require a very good vacuum, and they are expensive.

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• Mass Spectrometry separates atoms (actually ions) according to their differing masses.

• Neat websites!• http://www.chem.arizona.edu/massspec/

example_html/examples.html • http://www.cea.com/cai/simstheo/mspectra.htm • http://www.chemguide.co.uk/analysis/masspec/

elements.html

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The different elements have different masses.

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AtomsAFM and MS

• AFM – The AFM box allows students to mimic the measurements made with a real AFM. Maybe you can feel individual atoms?

• MS – The mass spectrometer allows students to mimic the measurements made with a real mass spectrometer. Do you want to see the trajectories of your atoms?

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AtomsMaking Stuff

• What does it cost?

• Atoms -- average cost is about $0.10 per atom (steel core costs $0.08 per atom)

• AFM -- $2-5 (most of the cost is velcro)

• MS -- $2

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Should I use this approach in my class?

• It (probably) will help students with the fundamental concepts of chemistry.

• Perhaps you are constrained by the sequencing of chemistry instruction?

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• Perhaps you are constrained by the sequencing of chemistry instruction?

• 8th grade ??? [pre-AP chemistry AP chemistry Freshman Chemistry degree in chemistry]

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• It (probably) will help students with the fundamental concepts of chemistry.

• Perhaps you are constrained by TEKS and TAKS?

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• Perhaps you are constrained by TEKS and TAKS?

• “Which letter in this model of a boron atom represents a neutron?” (TAKS grade 8 science April 2006)

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Comments

• Lots of ideas there

• It you use this material in the classroom, it may take you a month or more to work through the material.

• The “hands on” stuff will count as labs.

• No algebra! No exponents!

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What can we do together?

• Longer workshops on this theme?– Get 10 teachers together and ask me– Atoms (and how to make a set)? Density?

Gases and Pressure?

• Course at UTD “Lab and Demonstrations for Middle School” -- Spring 2009

• Research/publication on the effectiveness of this approach?

chemistry manipulatives for middle school students

Documents