Neat and Discrete
Carbon Nanoparticles
Carbon Chemistry
Far Out Application?
A space elevator-a new transport into
space?
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
2
Far Out Application?
The Proposal:
• A 62,000 mile long thin ribbon composed of an
incredibly strong carbon nanotube composite
• Anchored to a ship
• The ribbon is connected to a massive counterweight
on the other end that extends into space
• Electric vehicles ascend the ribbon, lifting
payloads from Earth to orbiting position
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
3
Far Out Application?
Why haven’t we already built a space elevator?
Answer: No materials were available that were
both strong and light weight enough.
Carbon holds the key…
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
4
Review: Carbon Chemistry
What elements on the periodic table are
most likely to form discrete nanoparticles?
• Those that form covalent bonds, elements to
the right of the transition metals (groups 13
through 16)
Why?
• These elements form covalently bonded
molecules with specific geometry.
• The central atom in these molecules form a
relatively small number of bonds to
neighboring atoms.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
5
Review: Carbon Chemistry
Characteristics of discrete nanoparticles:
• covalent bonding
• three-dimensional
• individual “gigantic” molecules
• non-extendable
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
6
Review: Carbon Chemistry
Let’s focus our attention mostly on
discrete nanoparticles made from
Carbon
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
7
Review: Carbon Chemistry
What is carbon’s electron orbital diagram?
How many bonds does carbon always form?
Four
These can be:
• four single bonds
• two single bonds and one double bond
• two double bonds
• one single bond and one triple bond
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
8
Review: VSEPR Theory
Four single bonds
• Tetrahedral with bond angles of
approximately 109º.
C Two single bonds and one double bond
• Planar with 120º bond angles.
=C= Two double bonds
• Linear with 180º bond angles.
C One single bond and one triple bond
• Linear with 180º bond angles.
C
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
9
What are Allotropes?
Allotropes are one of two or more forms of an
element in the same physical state.
What are the common allotropes of carbon?
Graphite
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
Diamond
10
Diamond
How are the carbon atoms arranged in diamond?
Each interior carbon is covalently bonded to four
others in a tetrahedron.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
11
Graphite
How are carbon atoms arranged in graphite?
• arranged in planar layers
(sheets)
• each interior carbon
atom is covalently bonded to three others in a
hexagonal pattern
• very weak forces exist between the layers (gray
lines in the figure above)
• the individual layers extend indefinitely in two
dimensions
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
12
Graphite
Knowing that:
1. carbon always forms four bonds;
2. each carbon atom in graphite is covalently
bonded to three other carbon atoms; and
3. the graphite layers are flat.
What is the bonding pattern around a given
carbon atom in graphite?
C
Two single bonds
C C and one double
bond
C
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
13
Graphite
In the mid 1980s scientists experimented by
vaporizing graphite using a laser. A new substance
was formed.
This is a diagram of
the first experiment
with graphite.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
14
Nanoparticles
Scientists knew the substance was carbon, but it
wasn’t graphite, diamond, or individual carbon
atoms.
So, what was it?
They proposed the formula of the material was C16.
How would chemists represent the structure of C16?
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
15
Nanoparticles
C16 fragment – a flat structure that does not
contain hydrogen
What is wrong with
this picture?
Hint: Remember, carbon
always forms four bonds.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
16
C ??
The product obtained in the lab was identified by
mass spectrometry. The mass spectrum of the
product is shown below.
How many carbon atoms
did the sample contain?
The evidence points to the
formula C60 (mass 720
amu).
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
17
C 60
Could the structure of C60 be
flat?
• No – just like the C16 fragment, a planar C60
structure would also have “dangling bonds”
on the outer edges.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
18
C 60
How can you bend a sheet of C60 to connect the
carbon atoms with dangling bonds?
Will it work to roll the sheet into a cylinder?
So what is the solution? Perhaps the answer can be
found by looking at an organic compound.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
19
Nanoparticles
Notice that this
molecule, corannulene
(C20H10), possesses a
single 5-membered ring
in addition to five
6-membered rings.
Clearly by adding a 5-membered ring, the
structure takes on a bowl-like shape with
curvature. Aha!
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
20
Buckyball
The mystery of C60
was finally solved.
This material incorporates
both 5-membered and 6membered rings.
It soon became known as a “buckyball” because it
resembles the famous architecture of Buckminster
Fuller.
The Nobel Prize in chemistry was awarded in 1996
for this work.
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
21
Making Connections
1. What are the characteristics of discrete
nanoparticles?
2. How does the arrangement of bonds
affect the molecular geometry for
carbon?
3. Describe the differences in how carbon is
arranged in graphite vs. diamond?
4. How might carbon nanoparticles be
useful?
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
22
Module Flow Chart
Lesson 1.1 What is
Nanoscience?
What is
Nanoscience?
Examine and
Compare size:
macro, micro, submicro (nano)
SI prefixes
Lesson 1.2 What
Makes Nanoscience
so Different?
Lesson 1.3 What
Makes Nanoscience so
Important?
What makes
Nanoscience so
different?
Compare Newtonian
and Quantum
Chemistry Regimes as
they relate to
nanoscale science
Interdisciplinary
science
The development of
new technologies and
instrumentation
applications whose risk
and benefits have yet to
be determined
Lesson 2.2 Extendable
Solids: Reactivity, Catalysis,
Adsorption
The difference between the
energy at the surface atoms
and energy of the interior
atoms results in increased
surface energy at the
nanoscale
Higher surface energy
allowing for increased
reactivity, adsorption and
catalysis at the nanoscale
Lesson 2.3
Extendable Structures:
Melting Point, Color
Conductivity
In Extendable Structures:
Melting point decreases because
surface energy increases
Color changes because electron
orbital changes with decreased
particle size
Electrical conductivity decreases
because electron orbital changes
with decreased particle size
Neat and Discrete Carbon Nanoparticles: Carbon Chemistry
© McREL 2009
Poster Assessment
Students will further
investigate the essential
question that they have
considered throughout the
module: How and why do
the chemical and physical
properties of nanosamples
differ from those of
macrosamples?
Lesson 3.1
Carbon Chemistry
Lesson 2.1 Extendable
Solids
As the size of the
sample decreases the
ratio of surface
particles to interior
particles increases in
ionic and metallic
solids
Lesson 3.2
Fullerenes and Nanotubes
The molecular geometry is
related to bond number and type
of bond (single, double, and
triple)
The requirement of four bonds
and their alternate resonance
structures is most significant in
the formation of carbon
allotropes
Different allotropes can have
very different physical and
chemical properties.
23