Microanalysis in Science and
Engineering
Identification Using
Microscopy and
Crystalline Structure
Biology and Chemistry
Contact Information
Clark George and Derek Mullican
Georgec@k12tn.net
derekmullican@hotmail.com
Warren County High School
199 Pioneer Lane
McMinnville, TN 37110
Performance Indicators
Chemistry II
Standard 1.0 Structure of Matter – 1.4 The student
will investigate the subject of ionic, covalent, metallic
bonds, and attractive forces between molecules.
1.5 The student will investigate the relationship of
chemical bonding to the state, structure and
properties of matter.
Biology
Standard 1.0 Cells – The student is able to
demonstrate appropriate use and care of compound
microscopes.
Textbook Reference(s)
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Biology: Principles and Explorations by
Johnson and Raven, Chapters 2 & 3.
Holt, Rinehart and Winston, 2001
Addison-Wesley Chemistry by Wilbraham,
Staley, Matta, and Waterman, chapters 15 &
16. Prentice Hall, 2002
Materials Needed
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Magnifying glass
Dissecting microscope
Light microscope
Access to internet and/or electron micrograph
images
Sugar
Salt
Other crystalline compounds, i.e. sodium thiosulfate
Glass of unsweetened tea
Bowl of unsalted popcorn
Rubric
CATEGORY
Components of the
report
2
One required element is
missing, but additional
elements that add to the report
(e.g., thoughtful comments,
graphics) have been added.
Question/Purpose
The purpose of the lab or the
The purpose of the lab or the
question to be answered
question to be answered
during the lab is identified, but during the lab is partially
is stated in a somewhat
identified, and is stated in a
unclear manner.
somewhat unclear manner.
Spelling, Punctuation One or fewer errors in spelling, Two or three errors in spelling, Four errors in spelling,
and Grammar
punctuation and grammar in
punctuation and grammar in
punctuation and grammar in
the report.
the report.
the report.
Participation
Used time well in lab and
Used time pretty well. Stayed Did the lab but did not appear
focused attention on the
focused on the experiment
very interested. Focus was
experiment.
most of the time.
lost on several occasions.
1
Several required elements are
missing.
Procedures
Procedures are listed in a
Procedures are listed but are
logical order, but steps are not not in a logical order or are
numbered and/or are not in
difficult to follow.
complete sentences.
Procedures do not accurately
list the steps of the
experiment.
Conclusion includes whether
the findings supported the
hypothesis and what was
learned from the experiment.
Conclusion includes what was
learned from the experiment.
No conclusion was included in
the report OR shows little
effort and reflection.
Lab report is neatly
handwritten and uses
headings and subheadings to
visually organize the material.
Lab report is neatly written or
typed, but formatting does not
help visually organize the
material.
Lab report is handwritten and
looks sloppy with cross-outs,
multiple erasures and/or tears
and creases.
Conclusion
4
All required elements are
present and additional
elements that add to the report
(e.g., thoughtful comments,
graphics) have been added.
The purpose of the lab or the
question to be answered
during the lab is clearly
identified and stated.
Procedures are listed in clear
steps. Each step is numbered
and is a complete sentence.
Conclusion includes whether
the findings supported the
hypothesis, possible sources
of error, and what was learned
from the experiment.
Appearance/Organiza Lab report is typed and uses
tion
headings and subheadings to
visually organize the material.
3
All required elements are
present.
The purpose of the lab or the
question to be answered
during the lab is erroneous or
irrelevant.
More than 4 errors in spelling,
punctuation and grammar in
the report.
Participation was minimal OR
student was hostile about
participating.
Special Notes
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Students already have experience in using
hand lenses, dissecting and light
microscopes.
Students have experience in writing lab
reports following this rubric.
Bond types and crystalline structures have
been covered in class.
Length: two 55-minute class periods.
Crystalline structures
Examining differences in crystal
forms of ionic and covalent
compounds
Engagement
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Observe the glass of tea and bowl of
popcorn.
Also, observe the salt shaker and the sugar
bowl.
In small groups, the learner will devise a
method to sweeten the tea and salt the
popcorn without resorting to tasting them,
using knowledge of crystalline structure, ionic
and covalent bonds.
Types of Magnifying Devices
Magnifying
glass
Dissecting
microscope
Light microscope
Scanning
electron
microscope
Ranges of Magnification
Exploration
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Use the magnifying glass, dissecting
microscope, and light microscope to explore
differences between the two substances.
Use what you know to predict the identity of
each substance based on what you see (do
not taste).
Design an experiment and record your
observations. Tasting allowed only at the
end of your exploration.
Light microscope image of salt
crystal
Light microscope image of sugar
crystal
Explanation
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As an ionic compound, salt (NaCl) exhibits
true crystal lattice structure, which can be
seen as perfect cubes when magnified.
Sugar (C12H22O11), while similar to salt to the
unaided eye, is a covalent compound and
forms a network solid rather than a true
crystal lattice. The irregularities may be
observed under a microscope.
Extension or Elaboration
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Use the internet to look up scanning electron
microscope images of crystals of sugar, salt,
and others. Ex:
gemini.tntech.edu/~jbiernacki
Record observations.
Use chemical properties and bond types to
explain why there are physical differences
between the substances.
SEM image of salt crystal
SEM image of sugar crystal
Evaluation
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Quiz over proper use of microscope.
Lab practicum to identify whether substances
are ionic crystals or covalent network solids.
Teacher and students use rubric to evaluate
and create formal lab report with students
hypotheses, procedures, observations, and
conclusions.
End Notes
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Many compounds have distinctive crystalline
structures that can aid in identification of the
substance.
The internet offers a wealth of information
and images that can help identify what is
seen under magnification.