Brown's Chemistry Revision Notes
NANOCHEMISTRY - Nanoscience - Nanotechnology - Nanostructures
Part 1. General introduction to
and commonly used terms explained
Alphabetical keyword index for
the nanoscience pages :
Index of nanoscience pages
: boron nitride *
Buckminsterfullerenes-bucky balls *
carbon nanotubes * fat nanoparticles
* fluorographene *
graphene * health and
* liposomes *
nanoscale * nanoscience *
* nanotechnology *
problems in nanomaterial use *
silver nanoparticles *
safety issues * sunscreens-sunblockers *
Part 1. General introduction to
and commonly used terms explained
The prefix 'nano' in the
context of the definitions-descriptions given below, and used on
this webpage, usually refers to dimensions-size of 1 - 100 nm. i.e. of
nanoscale (1 x 10-9
m to 1 x 10-7 m)
nm is the accepted
abbreviation for nanometre (nanometre) - more on the relative size of molecules and
bigger particles is given further down in a
comparison data table to put the nanoscale 'scene' in perspective.
For some ideas on scales and particle
sizes, and the table of examples further down the page.
Scale units for nanometres,1 nm = 1 x 10-9
m = 1 x 10-12 mm, so 1 nm is a millionth millionth of a
An individual atom has a diameter of
around 10-10 m (1 nm) and compare this with some examples of
Nanoparticles may contain just a few
hundred atoms, they are very very small ! Nanoparticles range in
size from 10-9 m to 10-7 m (1 nm to 100 nm).
particles (PM2.5), are larger than nanoparticles, and have diameters between 1 x 10-7 m and 2.5 x 10-6 m
(100 and 2500 nm).
Coarse particles (PM10),
are larger than fine particles with diameters from 2.5 x 10-6 m to 1 x 10-5 m (2 500
nm to 10 000 nm), course
particles are often referred to as fine dust particles.
Typical nanoparticles are roughly
spherical in shape, but the surface area to volume ratio is extremely
If you think of a simple cube, if the
side is decreased by a factor of 10, the surface to volume ratio increases
So nanoparticles have a very high surface
to volume ratio and this gives them special properties different from the bulk
This difference in surface area /
volume ratio for the particles of the material give nanoparticles
extra chemical reactivity compared to the bulk material,
less of a
material like a catalyst is needed in a chemical process, so catalysts based
on nanoparticles are more efficient than those based on bulk material
What is Nanoscience?
the branch of science concerned with the development and production and uses of materials whose
basic components are of nanoscale size, i.e. ~1 - 100 nm in size. Other more
specific terms which come under the general term 'nanoscience' are described
in more detail, particularly the term nanochemistry.
What is Nanotechnology?
methods for transforming matter, energy and information based on nanometre
scale (nanosized) components with particular defined molecular features and
prescribed physical and chemical properties.
techniques that produces materials with characteristic features with particle
sizes of ~1 - 100 nm and
involves advanced microfabrication techniques.
Nanotechnology is still based on
manufacturing processes that use typical chemical and mechanical principles
BUT in novel and unfamiliar situations (at least to those of us who were
graduate students in the late 60s!).
Nanotechnology creates and uses
structures that have novel properties because of their nanoscale small size.
Nanotechnology is developing from the ability to control
and manipulate at the atomic
scale, which essentially means controlling situations at the atomic and
molecular level, far removed from normal processing of bulk materials in a
typical laboratory or industrial process.
The use of the scanning tunnelling microscope
allows us to
'see' individual atoms in an atomic or molecular lattice in a way that was
inconceivable a 100 years ago when the principles of atomic and molecular
structure were being discovered.
So, it is now possible to see
and investigate nanoscale structures at the atomic-molecular level and this
'feedback' enables you to compare the actual structure with the desired
designed structure which eventually you would hope to have the prescribed
Does this advanced technology blur the distinction between
We are now well into CAD
(computer aided design) at the molecular level and there doesn't seem to any
limit (within the laws and principles of chemistry) as to what structures we
The many applications of nanotechnology
include the use
of semi-conductors that only conduct electricity in specific conditions and
allows the design of much very tiny 'devices' normal scale conductors, so the
final product can be much
smaller, enabling the design and use of faster smaller computers working at the molecular level.
It will be/is? possible to make
very tiny mechanical devices to perform some task in otherwise inaccessible
What are Nanostructures?
material structures assembled from layers or clusters of atoms of nanoscale
size i.e. ~1-100 nanometre. By controlling the size and assembling of
nanoscale constituents it is possible to alter and control the structure and properties of
the final nanostructure. The advantage of these new materials is that they
can be designed and built from the atomic level upwards to have specific
properties of great use to material scientists, a good example is the
ongoing development in the design and use
Nanocrystals may consist of over
1000 atoms but it can be quite variable within the 1-100 nm range.
applications of such nanostructures includes semi-conductor devices,
strained-layer lattices, magnetic multilayers.
Nanostructures are built up from
atomic or molecular precursors and processed via chemical deposition or physical vapour
deposition, gas condensation, chemical precipitation, aerosol reactions and
biological templating - a wide range of methods of assembling arrays of
Note that some nanoparticles
are created naturally e.g.
Very finely suspended mineral
particles in water - the tiniest of colloidal particles act as
During inefficient combustion of
organic molecules e.g. fossil fuels or plastics, nanosized particles of soot
(mainly carbon) are formed.
Evaporated seaspray can produce
nanoscale salt particles.
What are Nanomaterials?
Nanomaterials is a general word for any material that has a
composition based on nanoparticle units e.g. nanoparticles of silver,
carbon nanotubes, inorganic ceramic materials etc. more examples
As already mentioned
nanoparticles are usually in
the size range of 1 to 100 nm, described as being of nanoscale
Nanoparticles can be made of
elements, organic molecules, inorganic compounds, inorganic cluster compounds or metallic/semi-conductor
(maybe ~'semi-metal') particles.
Nanoparticles have a high
surface to volume ratio which has a dramatic effect on their properties
compared to non-nanoscale forms of the same material.
As a point of comparison, since
nanoparticles are in the size range 1 - 100 nm, a human
hair is 0.05 to 0.1 mm (50000 -100000 nm) in diameter, in other words nanoparticles
are usually 500 - 100000 times 'thinner' than a human hair!
1 nanometre (US nanometre),
1 nm = 10-9
of a metre (0.000 000 001 m, pretty small!)
Compared to other units:
1 cm = 10-2 m
(1 cm = 10000000 nm)
1 mm = 10-3 m
(1 millimetre = 1000000 nm)
1 μm = 10-6 m
(1 micrometre = 1000 nm)
1 nm = 10-9 m
1 pm = 10-12 m
(1 picometre = 0.001 nm)
So, when talking nanoscale
science, we are talking about pretty small structures!
More 'chemical structure' points
of comparison are given in the table below.
To put nanoparticles in
'size' or 'dimension' perspective, consider the table below of 'materials' -
pure elements, pure compounds and other more complex materials etc.
To put nanoparticles in
'perspective' i.e. what 'scale' are we talking about, I've put together a
size comparison table of various 'particles' in its broadest sense.
Data table of particles sizes/dimensions
of atoms, molecules, nanoparticles and other 'things', Nos 6
to 10 are typical nanoparticle size
typical small protein
||silver or titanium dioxide nano-particles
typical virus e.g. cold virus
||typical carbon nanotube
wavelength of visible light (comparison)
typical eukaryotic cell
width human hair
|Size in nm - diameter or length
0.3 x 0.6
50000 - 100000
longest length or diameter m
| 2 x
3 x 10-10
6 x 10-10
1 x 10-9
- Notes on the table
- na = not applicable i.e. no simple formula
or representation possible
- n = a large number of atoms or molecules
- Need diameter x length if
possible and revision of some of the data in the table above (microns?)
- Carbon is the basic atom or unit of
- Sulfur is a typical non-metal atom.
- Water is a relatively small molecule,
one of the smallest in fact.
- Silver is typical metallic lattice or
huge array of atoms, titanium dioxide is a giant lattice ionic lattice.
- Glucose is a molecule of 24 combined atoms of
carbon, hydrogen and oxygen atoms.
- Fullerene-60, a 'bucky ball', is the
precursor structure on which carbon nanotubes are based.
- A simple protein is a polymer of
alpha-amino acids [H2HCH(R)COOH]n where R is of
variable structure, n is a large number of peptide units-residues.
- Assume silver or titanium dioxide nanoparticles are
- A virus is a very simple organism, the simplest of
which consists of a strand of RNA in a protein sheath.
- A typical carbon nanotube might have a radius
of 3 nm and up to 100 nm long.
- The wavelengths of visible light are
typically 4 to 700 times bigger than most nanoparticles!
- A bacterium is a usually a single celled
cellular micro-organism and can contain over 5000 different molecules
- A eukaryotic cell is what all
multi-celled higher organisms are made up of.
- The human hair is easily recognised as
strands of a pretty thin material.
- Very fine dust particles have typical particle
diameter sizes of 1 x 10-5 m to 2.5 x 10-6 m
APPENDIX 1 An arithmetical investigation of the
relationship between surface area and volume
Its effectively an exercise in looking at one
of the most important properties of nanoparticle materials, namely, their very
high surface area to volume ratio.
Analysis of surface area :
volume ratio for selected nm cube sizes
|length of side nm
||area of one face nm2
||total surface area
||volume of cube nm3
||surface area / volume
||1 000 000
||1 000 000
||6 000 000
||1 000 000 000
Plainly, the smaller the length
of the side, the greater the surface area to volume ratio
You don't have to do all these
calculations to derive the pattern.
If L = length of one side of cube, L
x L =area of one face = L2, total surface area = 6L2
Volume = L X L x L = L3,
therefore surface area /
volume ratio = 6L2 / L3
So, giving a general rule,
as L decreases surface /
volume ratio increases.
The smaller the particle the
greater the surface area to volume ratio.
Another approach to this kind of arithmetical exercise is
to derive a simple equation from the
geometrical equations for a sphere.
This is a better approach than above as nanoparticles are
more likely to be nearer a spherical shape than a simple cube, though many
textbooks use the cube to illustrate the idea (because its simpler maths I
suppose). So, using r as the radius of the spherical particle, the final
equation is very simple!
surface area of a sphere = 4πr2
volume of sphere = 4/3πr3
area / volume ratio = 4πr2 / 4/3πr3
(π, 4 and r2 all cancel out, 3 goes to
top line, leaving 3/r)
So, you can
clearly see that as r gets smaller, the surface area to volume ratio increases.
Same result as in 1b:
The smaller the particles the greater
their surface area to volume ratio.
NANOSCIENCE - NANOCHEMISTRY INDEX
General introduction to nanoscience,
and commonly used terms explained
NANOCHEMISTRY - an introduction and potential
applications including catalysts
Uses of Nanoparticles of titanium(IV) oxide, fat and silver
From fullerenes & bucky balls to carbon nanotubes
graphene oxide and
Cubic and hexagonal boron nitride BN
Problems, issues and
implications associated with
see also INDEX
SMART MATERIALS PAGES
revision notes on nanochemistry should prove useful for the
new AQA, Edexcel and OCR GCSE (9–1) chemistry science courses. Keywords: uses applications
nanomaterials * nanoparticles * nanoscale * nanoscience * nanosize-nanosized
particles * nanostructures * nanotechnology * nanotubes * These revision notes
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