radioactivity Flashcards
(93 cards)
1
Q
what is in the nucleus of an atom
A
protons and neutrons
2
Q
the mass number is the
A
biggest number
3
Q
atomic number is
A
the number which tells you how many protons there are
4
Q
if an atom loses electrons it becomes
A
ionised
5
Q
the number of protons determines
A
which element an atom is
6
Q
is the atomic number always the same for an atom
A
yes
7
Q
the mass number tells you
A
the number of protons and neutrons in the atom
8
Q
an isotope is
A
an element with the same number of protons but different number of neutrons
9
Q
can an element have more than 1 isotope
A
yes
10
Q
some atomic nuclei can be unstable and
A
radioactive
11
Q
why are some nuclei unstable and radioactive
A
because of an imbalance of protons or neutrons in the nucleus
12
Q
how can unstable nuclei become more stable
A
by emiting radiation
13
Q
name of the process of radioactivity to make a nuclei more stable
A
radioactive decay
14
Q
radiation can be in the form of what (2)
A
high-energy particle or wave
15
Q
When an unstable nucleus decays, it emits
A
radiation
16
Q
The different types of radiation that can be emitted are:
A
Alpha (α) particles
Beta (β-) particles
Gamma (γ) radiation
17
Q
are these changes spontaneous and random
A
yes
18
Q
symbol for alpha
A
α
19
Q
An alpha particle is the same as a
A
helium nucleus
20
Q
why is an alpha particle is the same as a helium nucleus
A
because it consists of two neutrons and two protons
21
Q
symbol for beta
A
β−
22
Q
Beta particles are
A
high-energy electrons
23
Q
when are beta particles produced
A
during beta minus decay, when a neutron in the nucleus is converted into a proton, and emits a high speed electron
24
Q
symbol for gamma
A
γ
25
gamma rays are
electromagnetic waves
26
gamma rays have the ___ energy of the different types of electromagnetic waves
highest
27
Alpha (α), beta (β) and gamma (γ) radiation can be identified by their: (3)
Nature (what type of particle or radiation they are)
Ionising ability (how easily they ionise other atoms)
Penetrating power (how far can they travel before they are stopped completely)
28
alpha is stopped by
paper
29
ionising ability of alpha
high
30
beta particles are what
high energy electrons
31
beta is stopped by
aluminium foil or 10cm of air
32
ionising ability of beta is
moderate
33
gamma is what
an electromagnetic wave
34
gamma is stopped by
nothing
35
ionising ability of gamma
low
36
PRACTICAL- investigating penetrating power for different types of ionisation
- need a geiger-muller tube connected to a geiger counter
- without any sources present, measure background radiation over a period of one minute
- place a radioactive source a fixed distance away from the tube and take the reading of the count rate for 1 minute
- take some paper, alumunium and lead
- one at a time, place the absorbers between the source and the tube and take another reading of count rate for 1 minute
- repeat with other radioactive sources and depending on what they pass through, check if its gamma or beta or alpha
37
alpha particles have a mass number of _ and an atomic number of _
4
2
38
beta minus particles have a mass number of _ and an atomic number of _
0
-1
39
gamma has a mass and atomic number of
0
40
in alpha decay, what do you do
-4 and -2
41
in beta decay what do you do
add 1 to the bottom
42
how is ionising radiation detected
- geiger muller tube and photographic film
43
Photographic films detect radiation by becoming ____ when it absorbs radiation
darker
44
what is backround radiation
The radiation that exists around us all the time
45
the natural backround radiation we have comes from (2)
space and earth
46
sources of backround radiation (4)
radon gas (50%)
rocks and building materials (15%)
medical x-rays (13%)
food (11%)
47
2 types of backround radiation
Natural sources
Artificial (man-made) sources
48
radon gas comes from
Airborne radon gas comes from rocks in the ground, as well as building materials e.g. stone and brick
49
how is radon gas detected
Radon gas is tasteless, colourless and odourless so it can only be detected using a Geiger counter
50
cosmic rays come from
space (sun)
51
biological material and carbon 14
All organic matter contains a tiny amount of carbon-14
52
Radioactive material in food and drink
Naturally occurring radioactive elements can get into food and water since they are in contact with rocks and soil containing these elements
53
natural sources of backround radiation (4)
randon gas from rocks and buildings
cosmic rays from space
carbon 14 in biological material
radioactive material in food and drinks
54
Artificial Sources of Background Radiation (4)
nuclear medicine
nuclear waste
Nuclear fallout from nuclear weapons
Nuclear accidents
55
are natural backround waste usually a cause for concern
NO
56
nuclear waste in backround radiation
itself does not contribute much to background radiation, it can be dangerous for the people handling it
57
Nuclear medicine in backround radiation
In medical settings, nuclear radiation is utilised all the time
58
Nuclear fallout from nuclear weapons - backround radiation
Fallout is the residue radioactive material that is thrown into the air after a nuclear explosion, such as the bomb that exploded at Hiroshima
59
nuclear accidents backround radiation
Nuclear accidents, such as the incident at Chornobyl, contribute a large dose of radiation to the environment
While these accidents are now extremely rare, they can be catastrophic and render areas devastated for centuries
60
the activity of a radioactive source ____ over a period of time and is measured in ____
decreases
bequerels
61
The activity of a radioactive source decreases with time because
each decay event reduces the overall number of radioactive particles in the source
62
Activity is measured in
becquerels
63
Radioactive decay is a ___ process
random
64
half life is
the time taken for half of the radioactive nuclei in a sample to decay
65
half life for a given isotope is the same or different depending on size ?
same
66
does the line in a half life graph touch the x axis
no it gets closer but never touches it
67
alpha radiation is used in
smoke detectors
68
how do alpha particles work in a smoke detector
when there is no smoke, the alpha ionises the air forming charged particles which complete the circuit
when there is fire, smoke is produced which breaks the circuit as alpha particles are absorbed and air is no longer ionised, this causes the alarm to ring
69
use of beta radiation
for tracers
monitoring the thickness of materials
70
use of gamma radiation
destroys microorganisms on food and extends the usable lifetime of food
71
second use of gamma (medical)
to sterilise medical equipment
72
in beta radiation when monitoring the thickness of materials, what happens if its too thick
the reading becomes very low
73
in beta radiation when monitoring the thickness of materials, what happens if its too thin
the reading is very high
74
why do count rates change in a geigger muller counter ( beta)
thicker materials (lead) absorb more radiation while thinner ones absorb less
75
what slows gamma down
lead
76
what is contamination
the accidental or unwanted transfer of a radioactive substance onto or into a material
77
A substance is only radioactive if it contains
a source of ionising radiation
78
contamination happens when
a radioactive isotope gets onto a material where it should not be, and as a result the small amounts of the isotope in the contaminated areas will emit radiation and the material becomes radioactive
79
what is irridation
The process of exposing a material to ionising radiation
80
does irradiating a substance make it radioactive
NO
81
what can irradiating a substance cause
cells to be killed
82
contamination is usually an
accident
83
irradiation is usually
on purpose
84
example of irradiation
sterilisation of food or medical equipment
85
when is medical equipment irradiated
before being used in order to kill any micro-organisms on it before surgery
86
when is food irradiated
d to kill any micro-organisms within it to make it last longer
87
radiation can cause harm in two ways, what are they
irradiation and contamination
88
how is ionising radiation harmful to living things
- kills and ionises living cells ( tissue cells)
- mutations of cells
89
tissue damage through radiation usually happens by
high energy EM radiation (like gamma rays)
90
what happens in mutation of cells by radiation (3)
- atoms in the DNA are ionised
- DNA can mutate while repairing
- if they replicate then it means that they form a tumour
91
precautions that can be taken to reduce radiation waste (3)
- increase distance from source (which reduces intensity and chance of contamination)
- reduce time spent near the source (decreases amount of radiation recieved)
- shielding (reduces amount of radiation which reaches the user)
92
by-products of nuclear power production often have __ half lives
Meaning ...
LONG
they could remain a risk for thousands of years
93
what precaution is taken to get rid of by products of nuclear power production and why
storing them underground as it reduces the risk because not even gamma can pass through large amounts of earth and rock
