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Scheme of work – Cambridge International AS Level Physical Science (8780)
Ph6 PHYSICS
Unit 6: Modern Physics
Recommended prior knowledge
Students should be able to describe matter in terms of atoms, with a qualitative understanding of their behaviour. They should be able to model an atom as
electrons orbiting a positively charged nucleus.
Context
An understanding of the qualitative behaviour of atoms in matter is an aid to further more advanced studies. The topic is important in the understanding of the world
around us.
Outline
The unit starts with the development of atomic models; this is an excellent example of how theory and experiment go hand in hand, the one driving the other
forward. Later in the unit the nature of nuclear decay is studied, giving a first glimpse into the spontaneous and random world of quantum physics.
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
Candidates should be able to
There is a limited supply of past papers
for the 8780 examination, therefore all
examples of examination questions are
taken from Physics 9702 AS papers.
These reflect the type of question that
candidates are likely to meet in the
8780 examinations.
13(a)
v1 2Y05
identify and describe protons,
neutrons and electrons in terms
of their charges and relative
masses
Discussion and revision.
Cambridge International AS Level Physical Science (8780)
1
Syllabus ref
Learning objectives
Suggested teaching activities
13(b)
describe the historical steps
which led to the development of
the Rutherford model from the
Thompson ‘plum pudding’ model
of the atom:
Discussion: the 19th century idea of the atom as being indivisible and the
basic building block of matter, through the discovery of the electron
which led to the Thompson model.
Experiment: Thermionic emission using the Teltron diode.
(i) describe the principles of the αparticle scattering experiment
Discussion: Description of the principles of the α-particle scattering
experiment and conclusion drawn from it.
(ii) infer from the α-particle
scattering experiment the
Rutherford model of the atom
including the existence of the
small size of the nucleus
13(c)
describe a simple model for the
nuclear atom to include protons,
neutrons and orbital electrons.
13(n)
Describe the distribution of mass
and charges in an atom
13(b)
(iii)outline the development of
Bohr model of the atom
Learning resources
Teltron diode, HT supply unit,
milliammeter, leads.
air table, magnetic pucks
or
α-particle scattering model
site 8
site 9
Discussion: how to provide evidence for relative
size of nucleus
– relative size of masses and
charges
– protons and neutrons
– nucleus, orbital electrons
Discussion of observations of scattering linked to size of nucleus
Examples:
Oct/Nov 2010 9702 paper 22 question 7
Discussion: simple Bohr model of the atom, including the weaknesses of
the Rutherford Model which led to quantised atom with allowed
orbits/orbitals.
site 10
There is much on the internet on the development of the atom, one way
to cover this work is to instruct students to research specific topics and
then to lead discussions on their topics.
13(d)
v1 2Y05
distinguish between nucleon
number and proton number.
Discussion: distinction between nucleus,
nuclide and nucleon
nucleon number
proton number
Cambridge AS Level Physical Science (8780)
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Syllabus ref
Learning objectives
13(f)
use the usual notation for the
representation of nuclides.
13(p)
describe the contribution of
protons and neutrons to atomic
nuclei in terms of proton number
and nucleon number
13(o)
13(e)
13(q)
Suggested teaching activities
Deduce the number of protons,
neutrons and electrons
show an understanding that an
element can exist in various
isotopic forms, each with a
different number of neutrons.
appreciate that nucleon number,
proton number are conserved in
nuclear processes.
13(h)
represent simple nuclear
reactions by nuclear equations of
the form
14
7
13(i)
v1 2Y05
Discussion: nuclide notation
Discussion based on Neon-20 and Neon-22
Idea of isotopes
Calculation of percentage composition
Discussion: nuclear reactions
– conservation of charge / proton number
– conservation of nucleon number
distinguish between isotopes on
the basis of different numbers of
neutrons present
13(g)
N +
4
2
He →
17
8
O +
1
1
Learning resources
Examples:
May/June 2010 9702 paper 21 question
7(a) (b)
Oct/Nov 2011 9702 paper 21 question 7
[(b)(i)TWO not THREE]
May/June 2008 9702 paper 2 question
7
Example:
Oct/Nov 2011 9702 paper 21 question 7
[not (b)(i)]
H
use nuclear equations to solve
problems where there are two or
more decays in a chain
Examples:
Oct/Nov 2010 paper 23 question 9
May/June 2009 paper 21 question 7
Oct/Nov 2008 paper 2 question 8
Cambridge AS Level Physical Science (8780)
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Syllabus ref
Learning objectives
Suggested teaching activities
13(j)
show an appreciation of the
spontaneous and random nature
of nuclear decay.
Discussions: meaning of spontaneity
meaning of randomness
13(k)
infer the random nature of
radioactive decay from the
fluctuations in count rate.
Expt: demonstration of randomness
Simulation using dice
Learning resources
Radioactive source, G-M detector,
counter
Tray with large number of dice
(e.g.100+)
Discussion:
background count rate
correct procedure for obtaining a count rate
distinction between count rate and activity
13(l)
13(m)
v1 2Y05
show an understanding of the
nature and properties of α-, βand γ-radiations
(β+ is not included: β-radiation will
be taken to refer to β-).
deduce the behaviour of beams
of protons, neutrons and
electrons in electric fields
Comparison between α-, β- and γ- emissions with respect to
(i) nature of particle / photon
(ii) mass of particles
(iii) charge on particle / photon
(iv) energies of particles / photons
(v) speeds of particles / photons
(vi) degree of ionisation
(v) ranges in various materials
Radioactive sources, G-M detector,
counter, absorbers
Examples:
Oct/Nov 2011 paper 22 question 7
May/June 2010 paper 23 question 7
Oct/Nov 2009 paper 21 question 7
Example:
Oct/Nov 2011 paper 23 question 6*
*An interesting variation of this is to
substitute protons for alpha particles.
Cambridge AS Level Physical Science (8780)
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