Radioactive Decay Flashcards
State four types of nuclear radiation.
- Alpha particles
- Beta particles
- Gamma rays
- Neutron
What is meant by background radiation?
● Radiation that is always present
● It is in very small amounts and so not
harmful
Give 4 sources of background radiation.
- Rocks
- Cosmic rays from space
- Nuclear weapon testing
- Nuclear accidents
How do you measure and detect background
radiation?
- Photographic film
2. Geiger-Muller counter
How is photographic film used to measure radiation?
A photographic film turns dark when it absorbs
radiation. This is useful for people who work on
radiation as the more radiation they are exposed
to, the darker the film becomes. Therefore the
workers know when they have been exposed to
too much radiation.
How is Geiger-Muller tubes used to
measure radiation?
When the Geiger-Muller tube absorbs radiation it
produces a pulse, which a machine uses to count
the amount of radiation. The frequency of the
pulse depends on how much radiation is present.
A high frequency would mean the tube is
absorbing a large amount of radiation.
What constitutes of an alpha particle?
● Two protons and two neutrons
● It is the same as a helium nucleus
What is the range of an alpha particle through air?
Afew centimetres (normally in the range of 2-10cm).
What will block beta radiation?
● Athin sheet of aluminium
● Several metres of air
What will block gamma radiation?
● Several centimetres of lead
● Afew metres of concrete
Which type of radiation is most ionising?
Alpha radiation.
Which type of radiation is least ionising?
Gamma radiation.
How does gamma emission affect the mass/charge
of an atom?
Both mass and charge remain
unchanged
Describe the plum-pudding model of the atom
A sphere of positive charge, with the
negatively charged electrons distributed
evenly throughout it
Prior to the discovery of the electron, what was
believed about the atom?
The atom was believed to be indivisible
Which experiment led to the plum-pudding model
being discarded?
Rutherford’s alpha-Scattering
experiment
What is the name given to the currently accepted
model of the atom?
The Bohr model
Describe Rutherford’s experiment
● Alpha particles (charge +2) were fired at a thin
sheet of gold foil
● Most particles went straight through
● Some particles were deflected by small angles
(< 90º)
● Afew particles were deflected by large angles
(> 90º)
What are the conclusions of Rutherford’s
experiment?
● Most of an atom is empty space
● The nucleus has a positive charge
● Most of the mass is concentrated in
the nucleus
What happens in the process of beta plus decay?
A proton turns into a neutron and a
positron (in order to conserve charge)
What is the process called when a neutron changes
into a proton and an electron?
Beta minus decay
When alpha decay occurs, what happens to the
atomic number and the mass number of the atom?
● The atomic number decreases by 2
● The mass number decreases by 4
● Anew element is made since the
atomic number has changed
What effect does beta minus decay have on the
mass number and atomic number of a atom.
● The mass number stays the same as the total
number of neutrons and protons hasn’t changed
(one has just turned in the other).
● The atomic number increases since there is one
more proton.
