The descovery of the structure of the atom through the years of research

This is a short presentation describing the development of the structure of the atom. It includes Rutherforeds findings and the 'plum pudding' model etc.

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The discovery of the
structure of an
atom…read more

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John Dalton
He is most famous for this atomic theory. This theory contained five main points:
1. Elements are made up of tiny particles called
2. All atoms of a certain element are identical
3. All atoms of a certain element are different to
any other element
4. Atoms of a certain element can combine with
atoms of another element to form compounds
5. Atoms cannot be created, divided into smaller
parts, nor destroyed in the chemical process
His theory was not accepted at first but now it is proven to be true…read more

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JJ. Thomson
He conducted many experiments on electromagnetism and atomic particles. In 1906 he
was awarded the Nobel prize in physics for his research into the discharge of electricity
in gasses.
Thompson discovered that cathode rays travelled in straight lines except when they are
bent by electric or magnetic fields Because they bent away from a negatively charged
plate, Thompson concluded that these rays are made up of negatively charged particles,
we now call them electrons.
Thompson found that he could
produce cathode rays using
electrodes of various materials.
He then concluded that
electrons were found in all
atoms and are over a thousand
times smaller than protons.…read more

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JJ. Thomson
Thompson came up with the plum pudding
model. They didn't know the existence of
the nucleus in the centre .The plum pudding
model contained :
·the positively charged matter in the
atom evenly spread out
·the electrons buried inside.…read more

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Ernest Rutherford
Rutherford was known as `the farther of nuclear physics'. In 1911
Earnest Rutherford used beams of particles as projectiles to explore
the structure of matter. At that time however he did not have a
particle accelerator so he used the decay of radioactive elements,
to produce his beams of particles. Rutherford fired particles at thin
gold foil, to see what happened.
If the plum pudding model was correct then the
neutrons that were fired at the gold foil would have
passed straight through. Most of them did but, about
1/10000 particles were deflected by more than 90
He said "It was almost as incredible as if you fired a fifteen inch shell at a piece of tissue
paper and it came back and hit you."…read more

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Ernest Rutherford
He concluded that atoms in order for the alpha
particles to bounce right back they must hit
something small and dense. So his new model of the
atom was a little bit like the solar system. All of the
mass concentrated at the centre, and the electrons
orbiting like planets around the sun.
We know that it is not correct because quinton
mechanics tells us that we can not possibly know
precisely were the electrons are. But we can conclude
that they reside in distinct shells around the nucleus.
Alpha scattering disproved the
plum pudding model. The
alpha particles should have
passed straight through. But a
few deflected at large angles…read more

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