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Revision on pages 92-96, Questions - Coggle Diagram
Revision on pages 92-96
A key discovery yo
A french scientist found out that salt emitted radiation.
A french scientist discovered that uranium salts must of sent out some form of radiation that passed through that passed through the paper but not through the metal this was discovered by-mistake by a key had been in a draw under a key with a packet of uranium salts.
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Inside The Atom
About 100 years ago, a physist called Ernest Rutherford wondered what stopped raidiation.
To find out, he did some tests. He put different materials between the radioactive substance and a detector.
In doing this, he discovered 2 types of radiation:
Alpha Radiation
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His students - including Hans Geiger, inventor of Geiger counter - carried out further investigations
They put a narrow beam of alpha particles was directed at a thin metal foil, and were surprised to find that some of the particles rebounded from the foil.
proved that this happens as every atom has a positively charged nucleus - contains most of the mass of the atom.
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A Nuclear Puzzle
More alpha-scattering experiments showed that:
- the hydrogen nucleus has the least amount of charge
- the charge of any nucleus is shared equally between a whole number of smaller particles, each with the same amount of positive charge
The name proton was given to the hydrogen nucleus because scientists reckoned that every other nucleus contained hydrogen nuclei.
They also knew that the mass of every nucleus except for the hydrogen nucleus, is bigger than the total mass of its protons.
So, there must be an uncharged type of particle with about the same mass as a proton in every nucleus except the hydrogen nucleus.
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The evidence for this existence was found by James Chadwick - a physicist. He found it 20 yrs after Rutherford's nucleus discovery.
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Questions
Page 93
1
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b
Write 2 differences between radioactive atoms compared with the atoms compared with the atoms in a lamp filament
decay of radioactive atoms cannot be prevented, whereas in a lamp filament the atoms stop emitting radiation when the lamp is turned off
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2
a
i
The radiation from a radioactive source is stopped by paper. Name that type of radiation the source emits.
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ii
The radiation from a different source goes through the paper. Name the type of radiation this source emits.
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