73868
Radioactivity
- An introduction to radioactivity
- The term radioactivity was given to
uranium by Marie Curie who said that it
gave out radiation all the time
- 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
- Ernest Rutherford
discovered two types
of radiation:
- - alpha radiation
who’s symbol is α
- beta radiation
who’s symbol is β
- Scientists later
discovered a third
type, gamma
radiation, written γ
- Scientists later
discovered a third
type, gamma
radiation, written γ
- - alpha radiation
who’s symbol is α
- beta radiation
who’s symbol is β
- The nuclei of atoms of
radioactive elements are
unstable
- An unstable nucleus becomes stable by
emitting alpha, beta or gamma radiation – this
is known also as decaying
- An unstable nucleus becomes stable by
emitting alpha, beta or gamma radiation – this
is known also as decaying
- Ernest Rutherford
discovered two types
of radiation:
- 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
- The term radioactivity was given to
uranium by Marie Curie who said that it
gave out radiation all the time
- Alpha, beta and gamma radiation
- Alpha particles are helium nuclei, and cannot even penetrate a
human hand or piece of paper
- Beta particles are negative electron which can
penetrate a thin aluminium sheet
- Radiation from a radioactive substance can knock
electrons out of atoms. These atoms become charged
because they have lost electrons.
- Radiation from a radioactive substance can knock
electrons out of atoms. These atoms become charged
because they have lost electrons.
- Gamma rays are electromagnetic
waves which can penetrate some
concrete
- Beta particles are negative electron which can
penetrate a thin aluminium sheet
- Beta’s range is about 1m in air
- Gamma radiation’s range is
approximately 10,000km – but we
often say it is unlimited
- Alpha particles are helium nuclei, and cannot even penetrate a
human hand or piece of paper
- Radioactive half-life
- Atoms of elements can
contain identical amounts of
protons but different amounts
of electrons – these are
called isotopes
- The activity of a
radioactive substance is
the number of atoms
that decay per second
- The number of clicks per minute that a Geiger
tube detects from a radioactive substance is
the count rate
- The number of clicks per minute that a Geiger
tube detects from a radioactive substance is
the count rate
- The time taken for the count rate of a
radioactive substance to half is its
half-life
- The half-life of a radioactive
isotope is the time it takes:
- - for the number of nuclei of
the isotope in a sample to
half
- - for the count rare of the isotope
to fall to half its initial value
- - for the count rare of the isotope
to fall to half its initial value
- - for the number of nuclei of
the isotope in a sample to
half
- The activity of a
radioactive substance is
the number of atoms
that decay per second
- Atoms of elements can
contain identical amounts of
protons but different amounts
of electrons – these are
called isotopes
- Useful radiation
- Radioactivity can be harmful
to us and our skin, but it serves
some uses
- Automatic thickness
monitoring
- - if the thickness of the foil
increases too much, the detector
reading drops
- - the detector sends a
signal to the rollers to
increase pressure on the
metal sheet
- - if the thickness of the foil
increases too much, the detector
reading drops
- 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
- - This means that for a normal kidney the radioactive reading goes up then down
- - …and for a blocked kidney, the reading goes up and stays up
- Radioactive dating is a process where we can find out
how old things are by using radioactivity. There are two
types…
- Carbon dating is used to
find the age of ancient
wood and trees
- Uranium dating is used to
find the age of igneous
rocks
- Carbon dating is used to
find the age of ancient
wood and trees
- Radioactive dating is a process where we can find out
how old things are by using radioactivity. There are two
types…
- - …and for a blocked kidney, the reading goes up and stays up
- - This means that for a normal kidney the radioactive reading goes up then down
- Automatic thickness
monitoring
- Radioactivity can be harmful
to us and our skin, but it serves
some uses
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