Radioactivity

sanakaka2
Mind Map by , created over 6 years ago

GCSE Physics P1 Mind Map on Radioactivity, created by sanakaka2 on 05/06/2013.

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sanakaka2
Created by sanakaka2 over 6 years ago
Radioactivity
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Radioactivity
1 An introduction to radioactivity
1.1 The term radioactivity was given to uranium by Marie Curie who said that it gave out radiation all the time
1.1.1 We can use a Geiger counter to detect radioactivity, where the counter will click each time a particle from a radioactive substance enters the Geiger tube
1.1.1.1 Ernest Rutherford discovered two types of radiation:
1.1.1.1.1 - alpha radiation who’s symbol is α - beta radiation who’s symbol is β
1.1.1.1.1.1 Scientists later discovered a third type, gamma radiation, written γ
1.1.1.2 The nuclei of atoms of radioactive elements are unstable
1.1.1.2.1 An unstable nucleus becomes stable by emitting alpha, beta or gamma radiation – this is known also as decaying
2 Alpha, beta and gamma radiation
2.1 Alpha particles are helium nuclei, and cannot even penetrate a human hand or piece of paper
2.1.1 Beta particles are negative electron which can penetrate a thin aluminium sheet
2.1.1.1 Radiation from a radioactive substance can knock electrons out of atoms. These atoms become charged because they have lost electrons.
2.1.2 Gamma rays are electromagnetic waves which can penetrate some concrete
2.2 Beta’s range is about 1m in air
2.3 Gamma radiation’s range is approximately 10,000km – but we often say it is unlimited
3 Radioactive half-life
3.1 Atoms of elements can contain identical amounts of protons but different amounts of electrons – these are called isotopes
3.1.1 The activity of a radioactive substance is the number of atoms that decay per second
3.1.1.1 The number of clicks per minute that a Geiger tube detects from a radioactive substance is the count rate
3.1.2 The time taken for the count rate of a radioactive substance to half is its half-life
3.1.3 The half-life of a radioactive isotope is the time it takes:
3.1.3.1 - for the number of nuclei of the isotope in a sample to half
3.1.3.1.1 - for the count rare of the isotope to fall to half its initial value
4 Useful radiation
4.1 Radioactivity can be harmful to us and our skin, but it serves some uses
4.1.1 Automatic thickness monitoring
4.1.1.1 - if the thickness of the foil increases too much, the detector reading drops
4.1.1.2 - the detector sends a signal to the rollers to increase pressure on the metal sheet
4.1.2 Radioactive tracers can be used for medical purposes. Patients can drink a glass of water containing a small amount of a radioactive substance, if they want to test their kidneys. The substance would simply flow in and out of healthy kidney, but a blocked kidney would not allow the substance to exit for a lot longer
4.1.2.1 - This means that for a normal kidney the radioactive reading goes up then down
4.1.2.1.1 - …and for a blocked kidney, the reading goes up and stays up
4.1.2.1.1.1 Radioactive dating is a process where we can find out how old things are by using radioactivity. There are two types…
4.1.2.1.1.1.1 Carbon dating is used to find the age of ancient wood and trees
4.1.2.1.1.1.2 Uranium dating is used to find the age of igneous rocks

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