Radioactivity Active Recall ANSWERS:
1. How was the structure of Gold foil scattering experiement
the atom discovered by
Ernest Rutherford?
2. What did the experimental Thin sheet of goil foil, beam of alpha particles,
set up consist of in the detector of alpha particles.
alpha particle scattering
practical?
3. What were Rutherford’s - Most of the alpha particle went straight
results for the scattering through the foil
experiment? (3 findings) - Some were deflected less than 10 degrees
- A very small number were deflected at
angles greater than 90 degrees.
4. What did it suggest when Most of the atom is empty space
the majority of alpha
particles went straight
through the gold foil?
5. What did it suggest when There is a positive nucleus at the centre which
some particles were was causing some to repel
deflected through small
angles less than 10
degrees?
6. What did it suggest when a The nucleus is extremely small and is where
small number of alpha the mass and charge are concentrated.
particles deflected straight Therefore an atoms consists of small dense
back at angles of greater positively charged nuclei.
than 90 degrees?
7. How has the structure of Dalton- all matter made of atoms that are the
an atom changed over smallest matter and can’t be broken down
time? Describe the any further. Atoms of the same element are
changes from John identical; atoms of different elements are
Dalton’s model, JJ different.
Thompson’s Model, JJ Thompson- electron discovered, plum
Rutherford’s Model, Bohr’s pudding model where atoms consist of
Model and the Quantum positive and negative charges in equal
Mechanical Model. amounts so an atom is overall neutral.
Electrons said to be like currants in a plum
pudding uniformly distributed in a positive
sphere.
Rutherford- aimed positive particles to gold
foil, found that atoms were mostly empty
space and the nucleus contains most of the
mass and positive charges and these were
concentrated in the nucleus. Electrons
therefore orbit the nucleus.
Bohrs-electrons occupy shells or energy levels
around a nucleus at particular distances
Quantum Mechanical-nucleus surrounded by
an electron cloud, where the cloud is most
dense there is an electron. Later neutron was
discovered and added to the current atom
model.
8. Rank beta, alpha and Alpha, beta, gamma
gamma from most to least
, ionising
9. Rank beta, gamma and Gamma, beta, alpha
alpha from most to least
penetrating
10.What are helium particles 2 protons, 2 neutrons, 2 electrons
made up of?
11.When are alpha particles Large nuclei
emitted?
12.Where are alpha particles Nuclei
emitted from?
13.What is the most ionising Alpha
type of radiation?
14.Why is alpha the most Highest charge of +2e, produces most
ionising type of radiation? amount of ion pairs per mm in air so can do
most damage to cells than other types of
radiation.
15.Why is alpha able to do It is the most ionising
more damage to cells than
any other types of
radiation?
16.What does it mean for It travels the shortest distance in air before
alpha to be the least being absorbed
penetrating type of
radiation?
17.What range does alpha 3-7cm
have in air?
18.What barrier can stop Paper
alpha?
19.What are beta minus High energy electron emitted from nucleus
particles?
20.What are beta positive High energy positrons emitted from nucleus
particles?
21.Where do beta particles Nucleus
get emitted from?
22.Why are beta minus Nucleus has too many neutrons
particles emitted?
23.Why are beta positive Nucleus has too many protons
particles emitted?
24.What kind of ionising is Moderately
beta?
25.Why is beta only a It has a charge of 1e, so can do slight damage
moderately ionising type of to cells, less than alpha but more than
radiation? gamma
26.What kind of penetrating is Moderately
beta?
27.What is the range of beta 20cm-3m depending on their energy
particles in air?
28.What barrier can stop beta Mm of Aluminium foil
particles?
29.What are gamma rays? High energy electromagnetic waves
30.Why are gamma rays When a nuclei needs to lose some energy
emitted?
31.If a gamma ray hits It ionises the atom and knocks electrons out.
, another atom, what does it
do to the particles within
an atom and what does it
do overall to the atom?
32.If gamma transfers energy Chemical changes in materials, damage or kill
to other atoms, what does living cells.
this make them do to
materials and cells?
33.Which type of radiation is Gamma
least ionising?
34.Why is gamma the least It has no charge as it is an electromagnetic
ionising? wave so produces the least ion pairs per mm
in air.
35.Why is gamma used in Its less ionising than alpha or beta, so does
cancer radiotherapy, but less damage
beta and alpha aren’t?
36.What is the most Gamma
penetrating type of
radiation?
37.What is the range of a Infinite
gamma ray?
38.What barrier can stop Centimetres of lead, meters of concrete
gamma?
39.What law does gamma Inverse square law
radiation follow?
40.How is an alpha source Smoke detectors have an alpha emitting
used in smoke detectors? source which ionised nitrogen and oxygen in
the air. These ionised molecules can conduct
electricity can cause a current to flow. If
smoke enters the alarm, it absorbs the alpha
particles, reducing the current and therefore
the alarm sounds. The half life of the source is
large so doesn’t need to be replaced.
41.How is radiation used in Using beta radiation, the materials pass
thickness controls of through rollers which are controlled using
materials? sensors attached to a Geiger counter. the
thickness can be controlled by measuring how
much radiation passes through the material to
the counter and the rollers move accordingly
to increase or reduce pressure to the correct
thickness. A source with large half life is
chosen so doesn’t have to be replaced often.
42.Which radiation type is Beta
used to determine the
thickness of materials?
43.Why is alpha used in As alpha particles would be absorbed by the
thickness control? materials
44.Why isn’t gamma used in Gamma would pass through undetected
thickness control? through materials.
45.What property of radiation A large half life
must the beta have which
ensures it won’t need to be
maintained or replaced
1. How was the structure of Gold foil scattering experiement
the atom discovered by
Ernest Rutherford?
2. What did the experimental Thin sheet of goil foil, beam of alpha particles,
set up consist of in the detector of alpha particles.
alpha particle scattering
practical?
3. What were Rutherford’s - Most of the alpha particle went straight
results for the scattering through the foil
experiment? (3 findings) - Some were deflected less than 10 degrees
- A very small number were deflected at
angles greater than 90 degrees.
4. What did it suggest when Most of the atom is empty space
the majority of alpha
particles went straight
through the gold foil?
5. What did it suggest when There is a positive nucleus at the centre which
some particles were was causing some to repel
deflected through small
angles less than 10
degrees?
6. What did it suggest when a The nucleus is extremely small and is where
small number of alpha the mass and charge are concentrated.
particles deflected straight Therefore an atoms consists of small dense
back at angles of greater positively charged nuclei.
than 90 degrees?
7. How has the structure of Dalton- all matter made of atoms that are the
an atom changed over smallest matter and can’t be broken down
time? Describe the any further. Atoms of the same element are
changes from John identical; atoms of different elements are
Dalton’s model, JJ different.
Thompson’s Model, JJ Thompson- electron discovered, plum
Rutherford’s Model, Bohr’s pudding model where atoms consist of
Model and the Quantum positive and negative charges in equal
Mechanical Model. amounts so an atom is overall neutral.
Electrons said to be like currants in a plum
pudding uniformly distributed in a positive
sphere.
Rutherford- aimed positive particles to gold
foil, found that atoms were mostly empty
space and the nucleus contains most of the
mass and positive charges and these were
concentrated in the nucleus. Electrons
therefore orbit the nucleus.
Bohrs-electrons occupy shells or energy levels
around a nucleus at particular distances
Quantum Mechanical-nucleus surrounded by
an electron cloud, where the cloud is most
dense there is an electron. Later neutron was
discovered and added to the current atom
model.
8. Rank beta, alpha and Alpha, beta, gamma
gamma from most to least
, ionising
9. Rank beta, gamma and Gamma, beta, alpha
alpha from most to least
penetrating
10.What are helium particles 2 protons, 2 neutrons, 2 electrons
made up of?
11.When are alpha particles Large nuclei
emitted?
12.Where are alpha particles Nuclei
emitted from?
13.What is the most ionising Alpha
type of radiation?
14.Why is alpha the most Highest charge of +2e, produces most
ionising type of radiation? amount of ion pairs per mm in air so can do
most damage to cells than other types of
radiation.
15.Why is alpha able to do It is the most ionising
more damage to cells than
any other types of
radiation?
16.What does it mean for It travels the shortest distance in air before
alpha to be the least being absorbed
penetrating type of
radiation?
17.What range does alpha 3-7cm
have in air?
18.What barrier can stop Paper
alpha?
19.What are beta minus High energy electron emitted from nucleus
particles?
20.What are beta positive High energy positrons emitted from nucleus
particles?
21.Where do beta particles Nucleus
get emitted from?
22.Why are beta minus Nucleus has too many neutrons
particles emitted?
23.Why are beta positive Nucleus has too many protons
particles emitted?
24.What kind of ionising is Moderately
beta?
25.Why is beta only a It has a charge of 1e, so can do slight damage
moderately ionising type of to cells, less than alpha but more than
radiation? gamma
26.What kind of penetrating is Moderately
beta?
27.What is the range of beta 20cm-3m depending on their energy
particles in air?
28.What barrier can stop beta Mm of Aluminium foil
particles?
29.What are gamma rays? High energy electromagnetic waves
30.Why are gamma rays When a nuclei needs to lose some energy
emitted?
31.If a gamma ray hits It ionises the atom and knocks electrons out.
, another atom, what does it
do to the particles within
an atom and what does it
do overall to the atom?
32.If gamma transfers energy Chemical changes in materials, damage or kill
to other atoms, what does living cells.
this make them do to
materials and cells?
33.Which type of radiation is Gamma
least ionising?
34.Why is gamma the least It has no charge as it is an electromagnetic
ionising? wave so produces the least ion pairs per mm
in air.
35.Why is gamma used in Its less ionising than alpha or beta, so does
cancer radiotherapy, but less damage
beta and alpha aren’t?
36.What is the most Gamma
penetrating type of
radiation?
37.What is the range of a Infinite
gamma ray?
38.What barrier can stop Centimetres of lead, meters of concrete
gamma?
39.What law does gamma Inverse square law
radiation follow?
40.How is an alpha source Smoke detectors have an alpha emitting
used in smoke detectors? source which ionised nitrogen and oxygen in
the air. These ionised molecules can conduct
electricity can cause a current to flow. If
smoke enters the alarm, it absorbs the alpha
particles, reducing the current and therefore
the alarm sounds. The half life of the source is
large so doesn’t need to be replaced.
41.How is radiation used in Using beta radiation, the materials pass
thickness controls of through rollers which are controlled using
materials? sensors attached to a Geiger counter. the
thickness can be controlled by measuring how
much radiation passes through the material to
the counter and the rollers move accordingly
to increase or reduce pressure to the correct
thickness. A source with large half life is
chosen so doesn’t have to be replaced often.
42.Which radiation type is Beta
used to determine the
thickness of materials?
43.Why is alpha used in As alpha particles would be absorbed by the
thickness control? materials
44.Why isn’t gamma used in Gamma would pass through undetected
thickness control? through materials.
45.What property of radiation A large half life
must the beta have which
ensures it won’t need to be
maintained or replaced
