By Dawen Li, Shoieb Shaik, Scott Wehby
ABCs of Nano
– A big picture of nanoscience, nanotechnology, and nano-engineering
Key concepts: This module provides 6th – 8th grade middle school students with a basic
understanding of the Nano. With the knowledge evolution about everything in nano, the various
disciplines of nanoscience and nanotechnology have seen enormous growth and the advent of
various revolutionary technologies. In this module development with the help of 3D visualization,
the important concept and phenomenon such as, how small is “small”, why nano is a magic
number, the dramatic increase in surface area thereby exposed atoms by dicing a cube into tons
of tiny cubes at nanoscale. In addition to the introduction of the basic concepts of the
nanoscience, the module further define the difference among nanoscience, nanotechnology,
and nano-engineering. Nanoscience is the study of material properties and behaviors at the
magic nanoscale, which is different from bulk materials. Nanotechnology is developed for further
understanding the nanoscience, facilitating new discoveries in nanoscience (Figure 1). As the
application of nanoscience and nanotechnology, nano-engineering is established in making
products to benefit human life and our society.
Figure 1: Interdependent relationship between science and technology revolving in Nano.
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By Dawen Li, Shoieb Shaik, Scott Wehby
Therefore, in this module the concepts of nanoscience is first introduced, then the development
of nanotechnology, such as nano imaging, nanofabrication, material identification, finally
followed by nano-engineering with demonstration of “nano products”. Examples include
powder explosives, strong automobile tires, etc.
Material Supplies: plastic interlocking cubes for hands-on experiments.
ENGAGE and EXPLAIN:
Preparing students on metric system in length
Though most of the world uses the International System of Measurement, commonly referred to
the metric system, students in the United States are often not familiar with the metric system.
Therefore as part of the engage, a pre-survey is administered to find out what students know
about metric units and help them be familiar with them.
Table 1: Pre-Survey of Metric Units
Abbreviation
Full name
Example of Size
Rank: smallest to largest
mm
μm
m
nm
cm
The students will be asked to make a list of various metric units associated with length, and we
will give students actual metric measurement units in length for them to sort from the smallest
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By Dawen Li, Shoieb Shaik, Scott Wehby
to the largest (Table 1). The students are also encouraged to visualize different units of length
and give example of each unit size, such as “A centimeter is about the size of my pinky nail” or “A
meter is about the distance between outstretched arms.” After going through visualization and
brief discussion on the metric units in length, we are now able to help them make sense about
Nano.
Why magic nanoscale? How small is Nano?
As the starter, magic nanoscale is defined in the range of 1 to 100nm, in which novel material
properties and phenomena are observed. Then a big picture on “how small a nanometer is” will
be visualized with Figure 2 and a short movie clip. Finally, terms about nanoscience,
nanotechnology, and nano-engineering are well defined to assist students understanding the
difference between science, technology, and engineering. After students are able to visualize
nanoscale, the following activities will help them to explore the power of nano in terms of size
effect.
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By Dawen Li, Shoieb Shaik, Scott Wehby
Figure 2: The scale showing how small a nanometer is when compared with other small lengths
EXPLORE and ELABORATE:
i. Surface area to volume ratio
By cutting a cubic object, more surfaces are exposed to the outside, therefore increase the
overall surface area. Students will be shown a 3D visualization video to demonstrate surface area
increase. Since the total volume is the same as before the cutting, the surface area to volume
ratio for each small cubes must be increased. To explore the change in surface area to volume
ratio as an object is scaled down, students will use interlocking plastic cubes with universal side
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By Dawen Li, Shoieb Shaik, Scott Wehby
length of “1” to build some cubes and calculate surface area, volume, and surface to volume
ratio. Based on the calculations and observation from the tabulated results in Table 3, students
will finally come to a conclusion or rule about the scaling effect, that is, as the cube sizes are
systematically scaled down, the surface area to volume ratio increases. Furthermore, with the
guidance of teacher, students will also be asked to compare the surface area and the surface
area to volume ratio when an object with 1m side length is scaled down to extremely small
cubes, i.e. nanoparticles with 1nm side length.
Table 2: Explore increase of surface area to volume ratio as an object is down scaled
Cube size (length x
width x height)
4x4x4 sub-cubes
Surface area
Total volume
S/V ratio
Conclusion
3x3x3 sub-cubes
2x2x2 sub-cubes
1 sub-cube
A cube with 1m side
length
Above cube is cut into
1nm small cubes
A cube with 1nm side
length
ii. Percentage of surface atoms
Through a 3D visualization students will be demonstrated how the percentage of surface atoms
increases as a cube becomes smaller. For a 10X10X10 size cube as seen in Table 3, there are 488
surface atoms and the atoms lying inside are 512. With total atoms of 1000, the percentage of
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By Dawen Li, Shoieb Shaik, Scott Wehby
surface atoms becomes 48%. Students will tabulate the number of total atoms, surface atoms,
inner lying atoms, and calculate the percentage of surface atoms for the rest of the cubes.
Through this demonstration students will learn how scaling down in size, particularly to
nanometer range, will dramatically increase surface atoms, resulting in a strong chemical
reaction, such as catalyst and explosives in nano/micro powder.
Table 3: Explore increase of surface to overall atom ratio as an object is scaled down
Cube size (length x
width x height)
# of overall
atoms
# of surface
atoms
# of inside
atoms
Percentage
of surface
atoms
10x10x10 sub-cubes
1000
488
512
48
9x9x9 sub-cubes
729
386
343
53
8x8x8 sub-cubes
512
296
216
57
7x7x7 sub-cubes
6x6x6 sub-cubes
5x5x5 sub-cubes
4x4x4 sub-cubes
3x3x3 sub-cubes
2x2x2 sub-cubes
Note: sub-cube has dimension of 1x1x1 in universal unit.
iii. Material identification
This activity is developed in order for students to understand how the materials and elements
are identified using nanotechnology based on nanoscience. Each element has a specific atomic
number (# of protons and electrons), and electrons are located at discrete energy levels (shells)
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with low-energy electrons close to nucleus. As the atomic number varies, the difference in
energy between shells changes. These energy differences are specific to the atom, which is the
basis in theory (nanoscience) for element identification. Based on this basic principle of
nanoscience, nanotechnology was developed. With electron beam shining on a sample, for
example, copper (Cu) or silicon (Si), electrons on the inner shells (close to nucleus) could be
knocked off by the electron beam. The electrons in outer shells (high-energy electrons) could fill
the vacancy in the inner shell, becoming low-energy electrons. Because of energy conservation,
the energy loss from electron movement results in emission of X-ray photons. The photon
energy is exactly equal to the energy difference between two electron shells (electron energy
loss). Since the energy difference between electron shells is characteristic to the element, by
measuring the emitted photon energy (peak position), the element can be identified.
Figure 3: The measured X-ray photon energy (peak position) for element identification
With 3D visualizations students will see the spectrum (photon intensity versus energy) for
copper, silicon, and copper/silicon alloy. Based on the positions of peak photon energy, materials
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By Dawen Li, Shoieb Shaik, Scott Wehby
are identified. The electron movement due to bombardment from external electron beam and Xray photon emission will also be visualized. Students will notice that photons from electron
movement between two close shells have a red color, indicating low-energy photons; while
photons from electron movement between two far away shells have blue color, representing
high-energy photons.
EVALUATE:
1. How small is small? What is the nanometer size?
2. Why Nano is a magic scale?
3. In your words describe the difference between nanoscience, nanotechnology, and nanoengineering.
4. What is the size effects in terms of surface to volume ratio and quantum confinement of
nanoparticles?
5. Give some examples for application of nano powders?
6. Can self-assembly happens at macro-scale?
7. What tools can be used for nanofabrication and imaging?
8. List a few nano-products related to our daily life?
Background knowledge for teachers:
1. Nanoscale: The nanoscale, based on the nanometer (nm) or one-billionth of a meter,
exists specifically between 1 and 100 nm. In such size, novel material properties and
phenomena are observed, which are different from bulk materials.
2. Atom: An atom is a smallest particle of the element that retains the characteristics of that
particular element. Basically all the available elements in the nature are made up of tiny
particles called atoms.
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By Dawen Li, Shoieb Shaik, Scott Wehby
3. Electrons: Electrons are part of an atom that are negatively charged and moves around
the nucleus of an atom in orbits. An electron is much smaller than the proton and
neutron in size and mass. When an electron on the inner shell is knocked out, another
electron from outer shell will fill the vacancy, emitting a photon (X-ray). The photon
energy is characteristic to the atom element. That is, different materials emit photons
with different energy. Based on the measurement of photon energy, elements can be
identified.
4. Surface area and surface-area to volume ratio: For a cube of sides ‘a’, whose surface area
is ‘6 a2’ and the volume is ‘a3’, the surface-area to volume ratio is defined as Surface area/
Volume = 6 a2/ a3 = 6/a. As the size of cube is in nanoscale, the ratio could be reach to the
order of magnitude of billion.
5. Surface atoms and chemical reaction: The total surface area of a three-dimensional object
determines the total atoms participating chemical reaction. The bigger the surface area,
the faster the reaction, as the number of particles that can interact increases. As the
particle gets smaller, the surface to volume ratio increases, i.e. more percentage of atoms
are exposed to outside, resulting in strong chemical reaction. This explains why powder
normally reacts faster than lumps.
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