Download [2]-1 Atomic Theory

GK-12 NSF STARS
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Wonders of a Small Small Small World
Presented by:
Souheil Zekri
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Sunshine Standards and GLE’s
Standard 2: The student understands the basic principles of atomic
theory.
 Benchmark SC.A.2.2.1: The student knows that materials may be made of
parts too small to be seen without magnification.
Grade Level Expectations
The student:
Third
 1. uses a tool to observe and study minute details of objects (for example, hand
lens).
Fourth
 1. uses a variety of tools (hand lens, microscope) to observe and study minute
details of objects.
Fifth
 1. knows that materials may be made of parts too small to be seen without
magnification.
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Lesson Layout
Classification of Materials
History of Materials
Atoms and Molecules and Nanotechnology
Microscopes
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Classification of Materials
Metals and Alloys
Ceramics, glasses, and glassceramics
Polymers
Semiconductors
Composite materials
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Metals and Alloys
 Metals are ductile (easily formable),
strong, good conductors of heat and
electricity:
– Aluminum, Chromium, Nickel,
Copper, Iron, Titanium, etc…
 Alloys are combinations of metals
made to improve the physical
properties of certain metals metal
such as:
– Bronze (combination of copper
and tin)
– Brass (copper and zinc)
– Steel (Iron, Carbon, Manganese,
Tungsten, Chromium, Nickel,
Cobalt…)
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Ceramics and Glasses
 Ceramics and Glasses are
brittle (brake easily on
impact), hard, bad heat and
electric conductors (usually
used as insulators):
– Quartz (SiO2)
– Titanium carbide (Titanium
mixed with carbon elements).
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Polymers
 Polymers (poly means many) are
divided into plastics and
elastomers:
– Plastic (when deformed they
don’t return back to its original
shape): group of synthetic
materials processed by heating
and forming or molding into
shape (ex: Nylon)
– Elastomers (natural rubber):
is elastic (could stretch and get
back to its original shape)
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Semiconductors
 Semiconductors are used in
electronics (game boy, XBOX,
PS2, computers…).
 Semiconductors can act as
conductors and insulators at
the same time.
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Composite Materials
 Composites are formed
from two or more
different materials that
could be metal, ceramic,
or polymer (ex:
fiberglass, concrete,
etc…)
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History of Materials: a time line
Matter divided into Idea of the
water, earth, air fire atom is born
Alchemy Periodic
table
is born
Modern atomic theory
Adapted from: http://people.clarityconnect.com/webpages/terri/history.html
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Early classification of Matter
 The Greek Empedocles of
Agrigente divided matter
into 4 elements and calls
them roots around 492432 BC:
–
–
–
–
Water
Earth
Air
Fire
 Aristotle thought that all
matter using ratios of the
four basic elements.
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Early concept of atoms
 Leucippe of Milet invents the
notion of atom or "a-tomos" in
Greek, which signifies
"indivisible". in 420 before J.C
 His disciple, Democritus of
Abdere (around 460-370 BC.),
explained that matter was made
up of particles in perpetual
motion.
http://perso.club-internet.fr/molaire1/e_histoire.html
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The Alchemy of the middle ages
During the 8th and 9th century
Jabir ibn Hayyan and ibn Sina
developed many of the concepts
of Al-kemia arabic for Alchemy,
which marks the birth of
Chemistry and Pharmacy.
Medieval European scientists
used their principles to develop
further understanding of matter
and its composition.
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Mendeleev’s first periodic table
 In 1869 Dmitri I.
Mendeleev published
the first periodic table
that organized elements
in groups with similar
characteristics.
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Modern periodic table periodic table
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The Atom: Bohr’s atomic model
Electron
Neutron
Nucleus
Proton
Hydrogen Atom
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Today’s atomic model
Region where electron will
most probably be
Region where electron
has less probability to
exist
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What is Air Made Out of?
21%
78%
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Water Molecule
 A molecule is the simplest
unit of a chemical
compound that can exist,
consisting of two or more
atoms held together by
chemical bonds
 A water molecule consists
of one oxygen atom and two
hydrogen atoms
Picture courtesy of http://www.lsbu.ac.uk/water/molecule.html
105o
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What is a Nanometer
3 ft = 1 meter
1meter = 1000 millimeter
1 millimeter = 1000 micrometer
1 micrometer = 1000 nanometer
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Entering the Nanoworld
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How Would a Nanometer Compare to Human Hair?
~ 1 nanometer
100,000 nanometers
Human hair magnified 1000 times: courtesy of
http://acept.la.asu.edu/PiN/rdg/elmicr/optical.shtml
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Atomic Geometry
One Proton (or Neutron) weighs about 1,835 times larger than an electron!!!
Most of the atom is empty with a very dense nucleus
The nucleus is so dense that if we took only nuclei and packed them into
a ½ inch cube, the cube would weigh 133,000,000 tons!
If we increase the nucleus to the size of a pea, the electron would be
about ½ a mile a way from it.
3 x 10-24 grams
9.10 x 10-28 grams
1 x 10-18 m = 0.000000005 nanometer
5 x 10-15 m = 0.000005 nanometer
5 x 10-11 m = 0.05 nanometer
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So What do we Use to See an Atom?
 Certainly not light microscopes!
 We use Electron microscopes.
Picture of a moth wing magnified 15,000 times
courtesy ofhttp://www.mos.org/sln/sem/moth.html
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Pictures of atoms
Quantum corral of Iron on Copper (111) (Physics Today 46 (11), 17-19 (1993).
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Nanotechnology
Science and technology applied to the
nanoscale, which varies from 100 nanometers
to 1 nanometer.
Make faster and smaller computers
Help medicine by making small nanorobots
that travel through blood stream
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