RADIOACTIVITY
Structure
of the atom Yr.
11 1. Rutherford
scattering experiment. § Characteristics
of radioactivity Yr
11 Radioactivity
is the spontaneous emission of energy from atomic
nuclei. Radioactivity is the
result of the breakdown of unstable nuclei. Radioactivity is a random
process unaffected by physical or chemical
factors. Use of Geiger-Müller
counter (GM
counter) and counter to detect and measure radiation
[Details of how they work is not
required] Use of photographic
film to detect
radiation § Background
radiation Yr
11 1 Natural background
radiation is
due to: (i) radioactivity of
naturally occurring isotopes in rocks at the surface or
within the Earth (ii) radiation from space
2 The effect of human
activity on background radiation § Types
of emission Yr
11 Alpha
particles
(symbol a
) are emissions with low penetrating power blocked by
paper Beta
particles
(symbol ß
) are emissions with moderate penetrating power blocked by
thin sheets of aluminium. Gamma
radiation
(symbol g
) is an emission
with high penetrating power blocked by
concrete/lead. Gamma radiation is part of
the electromagnetic
spectrum and
has very high frequency. An alpha
particle is a helium nucleus emitted by an unstable
nucleus A Beta
particle is a high energy electrons by an unstable
nucleus Transformation
of nucleus following decay. Half-life Yr
11 Half-life
is the time taken for half a given number of radioactive
atoms to decay to different atoms Use of
data to determine the half-life of a radioisotope Use of
half-life in dating materials Effects
of radiation Yr.
11 Harmful effects of
radiation on living organisms, limited to cell damage as a
cause of cancers. § Uses
of radioactivity Yr
11 1. Use of radioactive
isotopes (i) quality control in
industry (ii) in treatment of
cancers 2. Social, economic and
environmental problems associated with an increase in the
use of radioactive materials. Tracers in
medicine and in industry Nuclear
energy Yr
11 The
process of nuclear
fission
GCSE syllabus: electromagnetism
Date Last
Modified: April
2003
Emanuel School, London SW11 !HS
All text and diagrams copyright of J.C.Naylor