GCSE physics - atomic structure and radiation
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20 Terms
State the the three particles that make up an atom, their charge and where they are found.
Proton: +1 charge, in the nucleus
Neutron: no charge, in the nucleus
Electron: -1 charge, around nucleus in energy levels
State what happens when an electron absorbs electromagnetic radiation
Excitation occurs, so the electron moves to a higher energy level
What is meant by activity?
The rate at which a source of unstable nuclei decays
What is meant my count rate?
The number of decays each second that a detector actually records
What is radioactive decay?
Some nuclei are unstable, so it gives out radiation as it changes to become more stable. This is radioactive decay
What is activity measured in
Becquerel (Bq)
Geiger-Muller tube
The device that detects count rate from a radioactive substance
the four types of nuclear radiation
Alpha
Beta
Gamma
Neutron
Alpha particle
Two neutrons and two protons.
Beta particle
A high speed electron ejected from the nucleus as a neutron turns into a proton
Irradiation
The process of exposing an object to nuclear radiation. The irradiated source does not become radioactive!
Radioactive contamination
The unwanted presence of materials containing radioactive atoms on other materials.
Why is radioactive decay random
It is impossible to predict which nucleus in a sample will decay next
It is impossible to predict when any particular nucleus will decay
Every undecayed nucleus has the same chance of decaying as the next, however long it has already existed
Half life of a radioactive isotope
The time it takes for the number of nuclei of the isotope in a sample to halve.
What does it mean to have a short half life
Nuclei decay quickly, so many decays happen each second
The activity is high
The source is more dangerous now, but it decays away quickly
What does it mean to have a long half life
Nuclei decay slowly, so fewer decays happen each second
Activity is low
The source is less dangerous now, but it stays radioactive for a very long time