1. B Y
G . M A H A L A K S H M I M A L I N I ( A P / E C E )
F A C U L T Y O F E N G I N E E R I N G
A V I N A S H I L I N G A M I N S T I T U T E F O R H O M E S C I E N C E
A N D H I G H E R E D U C A T I O N F O R W O M E N
Background to Nanotechnology
2. CONTENTS
Types of Nanotechnology and Nanomachines
Periodic table
Atomic structure
Molecules and phases
3. Types of Nanotechnology and
Nanomachines
A silicon chip and some copper wire form a
microcircuit that can be used with other
components to form a computer. These are
micro machines
In human there are huge number of machines
that convert carbohydrates to carbon dioxide
and use the energy generated to perform
functions. These are also considered as nano
machines.
4. Periodic Table
The periodic table is an arrangement of atoms
called elements.
The periodic table shows 109 elements
Each element has a symbol eg: H for Hydrogen, Ca
for Calcium.
The vertical columns of the periodic table are
called groups.
The horizontal rows are called periods
6. Contd..
First group elements are called alkali metals (Li, Na, K,
Rb, Cs, Fr)
the alkali metals are group (column) in the periodic
table consisting of the chemical elements lithium (Li),
sodium (Na), potassium (K), Rubidium (Rb), Caesium
(Cs), and francium (Fr).
The 18th group of elements are called nobel gases (He,
Ne, Ar, Kr, Xe, Rn)
the six nobel gases that occur naturally are helium
(He), heon (Ne), argon (Ar), Krpton (Kr), Xenon (Xe),
and the radioactive radon (Rn)
7. Atomic Structure
Elements:
an element consist of only one type of atom
John dalton, in 1807 proposed an atom model and the postulates
of dalton’s atomic theory are.
1) elements are composed of indivisible particles
called atoms.
2) all atoms of a given elements are identical
3) chemical compounds are formed when atoms
combines with each other.
4) Chemical reactions involve reshuffling of atoms
from one set of combinations to another. The atoms
themselves are not changed in a chemical reaction.
8. Limitations of Dalton’s atomic Theory
Dalton considered the atom to be indivisible, but
however there are three major fundamental
subatomic particles: electrons, protons, and
neutrons.
The protons and neutrons are collectively known
as neutrons.
Electrons are negatively charged particles and
protons are positively charged particles.
Neutron have no charge.
9. Rutherford Atom Model
Ernest rutherford proposed a planetary model of
the atom
The atom consists of a positively charged core
called a nucleus.
The negatively charged electrons travels in a
circular orbits around the nucleus.
10. Bohr’s Atom Model
In an atom, the electrons revolve around the
nucleus in certain circular paths called orbits and
shells.
The electrons present in an atom can move from a
lower energy level to a higher energy level by
absorbing the appropriate energy.
Similarly an electron can jump from higher energy
level to lower energy level by losing appropriate
energy.
11. Molecules and Phases
Phases are states that define their properties such as
liquids, gases and solids.
Molecules are collections of atoms bound to each other and
that exists in these phases.
molecules are formed by atoms in one of two ways.
One ways is called sharing of electrons. This type of
combination is called a covalent bond.
Secondly the molecules can be formed by transferring
electrons between atoms.
the atom losing the electron is positively charged and the
atom gaining the electron is negatively charged.
12. Energy
E = mc2
E= energy
M= mass of matter
C= speed of light
Light and heat are examples of different forms of
energy
13. Contd….
Some forms of energy have properties of both
matter and waves. This is called dual nature of
energy.
The debroblie’s equation expresses the relationship
between wavelength (λ) and mass (m)
λ = h/mv
h = planck’s constant
v= velocity of wave
14. Molecular and Atomic Size
Nanotechnology involves working with materials
around metres in size .
The size of the atoms increases on moving from top
to bottom on the periodic table.
The size of an atom changes considerably when it
loses an electron (ionises).
15. Surfaces and Dimensional Space
One dimensional – line
Two dimensional – plane
Three dimensional – volume
Nanotechnology is concerned with single layers of
atom on surafces.
16. Top down and bottom up
There are two different approaches to creak very
small machines or devices.
In top – down approach, a block of material is taken
and whittling it away to the object that is wanted .
In bottom up approach, individual atoms and
molecules are placed or self assembled precisely to
produce bigger objects.
