chemistry manipulatives for middle school students
DESCRIPTION
Chemistry Manipulatives for Middle School Students. Lynn A. Melton University of Texas at Dallas [email protected] CAST November 6, 2008. Website. http://www.chemchapterzero.com The concepts are presented in greater detail. PowerPoint presentations can be downloaded. - PowerPoint PPT PresentationTRANSCRIPT
1
Chemistry Manipulativesfor Middle School Students
Lynn A. MeltonUniversity of Texas at Dallas
[email protected] 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 #1:Atomic 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 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
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
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.
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, let’s 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/
elements.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?