Chemistry Manipulatives for Middle School Students

1
Chemistry Manipulativesfor Middle School Students

• Lynn A. Melton
• University of Texas at Dallas
• melton_at_utdallas.edu
• CAST November 6, 2008

2
Website

• http//www.chemchapterzero.com
• The concepts are presented in greater detail.
• PowerPoint presentations can be downloaded.

3
Fundamental Concepts ofChemistry

• Atoms
• Bonding/Molecules/Reactions
• Structure/Properties
• Activity of molecule derives from its structure

4
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 .

5
Atoms Key Question

• Your answer .
• Define an atom carefully
• Data 1Atomic Force Microscopy
• (the world is granular)
• Data 2 Mass Spectrometry (the particles
  have different weights)
• Work on Seeing Without Seeing

6
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.

7
AtomsDigression

• Words that may come up. (If they dont ask, dont
  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

8
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.

9
Lets 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, lets work on Seeing Without Seeing.

10
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?)

11
AtomsSeeing Without Seeing

• 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.

12
AtomsSeeing Without Seeing

• 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?

13
AtomsSeeing Without Seeing

• 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.

14
AtomsSeeing Without Seeing

• 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.

15
AtomsSeeing Without Seeing

• Now, the whole group discusses their results.
• This is our version of an international
  scientific meeting.

16
AtomsSeeing Without Seeing

• Hands On Time!
• Go to it!

17
AtomsSeeing Without Seeing

• Switch bags with another team.
• Each team analyzes the other sample.

18
AtomsSeeing Without Seeing

• Now, all together, lets discuss the results.

19
AtomsSeeing Without Seeing

• On Planet Xanadu, is there a periodic table?

20
AtomsSeeing Without Seeing

• 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?

21
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.

22
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

23
AtomsWhat AFM data do we have?
Silicon surface
24
AtomsWhat AFM data do we have?
NaCl (salt) surface
25
AtomsWhat AFM data do we have?

• Conclusion
• The world feels granular.

26
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.

27
AtomsWhat MS data do we have?

• 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/elemen
  ts.html

28
AtomsWhat MS data do we have?
The different elements have different masses.
29
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?

30
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

31
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?

32
Should I use this approach in my class?

• Perhaps you are constrained by the sequencing of
  chemistry instruction?
• 8th grade ????? pre-AP chemistry ? AP
  chemistry ? Freshman Chemistry ? degree in
  chemistry

33
Should I use this approach in my class?

• It (probably) will help students with the
  fundamental concepts of chemistry.
• Perhaps you are constrained by TEKS and TAKS?

34
Should I use this approach in my class?

• 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)

35
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!

36
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?