Download Ideas about Atoms

by
Erdal ERSOY
Your task
 Make a PowerPoint presentation on how our ideas about
atomic structure have changed over the last 2500
years.
 This template will help you.
 There is information on page 372 in Physics for You.
Your teacher may give you an Extension Sheet with some
facts.
You can find more from the Internet. See the next slide to
find out how.
Democritus
 Democritus thought
matter could not be
divided infinitely.
 But he had no proof.
 He did this by dividing
a cheese into pieces
until it couldn’t be
divided by a knife.
John Dalton
Dalton’s elements that we still
think of as elements today;
DALTON’S MODEL OF ATOM
 All matter is made of atoms.
 Atoms of an element are
Hydrogen,Carbon,Nytrogen
Oxygen,Phosphorus,Shulphur
identical
 Each element has different
atoms.
Iron,Zinc,Copper,Lead, Gold,
 Atoms are rearranged in
Platine, Mercury
reactions.
J. J. Thompson
 In this model, the atom is composed of
electrons surrounded by a soup of
positive charge to balance the electron's
negative charge, like negativelycharged "plums" surrounded by
positively-charged "pudding".
 Thompson’s experiment was important,
and kick-started an entire wave of
discovery of sub-atomic particles,
including the next step in
understanding the atom – the discovery
of the atomic nucleus.
Brownian Motion Theory
 The importance of the theory lay in
the fact that it confirmed the kinetic
theory's account of the second law of
thermodynamics as being an
essentially statistical law.
 We know that a water molecule is
about 0.1 by 0.2 nm in size, whereas
a pollen particle is roughly 25 µm in
diameter, some 250,000 times larger.
So the pollen particle may be
likened to the balloon, and the water
molecules to the fans except that in
this case the balloon is surrounded
by fans.
Ernest Rutherford
 JJ Thompson’s ‘plum-pudding’ says that
negative electrons are in a positive
framework.
Find an image of
Ernest Rutherford
and place it here.
 The Rutherford’s method says that atoms
are mostly empty space and negative
electrons orbit a positive nucleus.
Alpha-particle scattering
GEIGER and MARSDEN
 Rutherford had a large water
tank installed on the ground
floor of the building in
Manchester, to carry out
research on defense against
submarine attack. Nevertheless,
occasional research on alpha
scattering continued.
Scattering from heavy nuclei
was fully accounted for by the
electrostatic repulsion, so
Rutherford concentrated on
light nuclei, including
hydrogen and nitrogen.
James Chadwick
 As they studied atomic
disintegration, they kept seeing
that the atomic number was less
than the atomic mass. For
example, a helium atom has an
atomic mass of 4, but an atomic
number of 2. Since electrons have
almost no mass, it seemed that
something besides the protons in
the nucleus were adding to the
mass. He called them neutrons.
 Isotopes is the atoms which has
same atomic number but different
neutron number.
Quarks
Try to find an image for here,
that will help to explain.
QUARKS
 Quarks combine to
form composite
particles called hadrons, the most
stable of which
are protons and neutrons, the
components of atomic nuclei. Due
to a phenomenon known as color
confinement, quarks are never
found in isolation; they can only
be found within hadrons.
MURRAY GELL-MAN’S IDEAS
 Murray Gell-Mann found that all of those particles, including the
neutron and proton, are composed of fundamental building blocks
that he named "quarks." The quarks are permanently confined by
forces coming from the exchange of "gluons." He and others later
constructed the quantum field theory of quarks and gluons, called
"quantum chromodynamics," which seems to account for all the
nuclear particles and their strong interactions." ...

Extra
Task
Democritus (440 BC) suggested the idea of atoms but with no proof.
Eventually Robert Boyle’s experiments (1662) supported the idea and in
1738 Daniel Bernoulli proposed the kinetic theory.
 John Dalton used atomic weights (1805) to support the idea, and in 1831
Thomas Graham investigated diffusion.
 Henri Becquerel discovered radioactivity (1896) and Marie Curie
discovered radium (1898). Ernest Rutherford discovered alpha and beta
rays. Rutherford came up with the idea of an atomic nucleus.
 Niels Bohr (1913) suggested the idea of electrons in orbits with different
energies.
 Write a slide or more about the new ideas that each of these scientists
brought to the topic.
References
 http://web.mit.edu/philos/www/mm/democritus.jpg
 http://en.wikipedia.org/wiki/Plum_pudding_model
 http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Plum_pudding_atom.svg
/348px-Plum_pudding_atom.svg.png
 http://www.coolfusion.com.au/img/LASERScan_2.png
 http://en.wikipedia.org/wiki/Brownian_motion
 http://www.scientific-web.com/en/Physics/Biographies/images/ErnestRutherford2.jpg
 http://web.educastur.princast.es/proyectos/grupotecne/archivos/investiga/145chadwick.
jpg
 http://en.wikipedia.org/wiki/Quark
 http://en.wikipedia.org/wiki/File:Quark_structure_proton.svg
 http://www.osti.gov/accomplishments/gellmann.html