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Physics > Topic 6 Radioactivity (complete) > Flashcards

Topic 6 Radioactivity (complete) Flashcards

(62 cards)

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1
Q

What is the nucleus made of

A

Protons and neutrons therefore has a positive charge

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2
Q

Where is most of the mass of an atom

A

In the nucleus

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3
Q

What surrounds the nucleus

A

Shells of electrons

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4
Q

What is an isotope of an element

A

Atom with same number of protons (same atomic number) and different number of neutrons (different mass number

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5
Q

13
C
6
Which is the mass and atomic number

A

Atomic number 6
Mass number 13

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6
Q

What is the charge of a
Electron
Proton
Neutron

A

Electron negative
Proton positive
Neutron no charge

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7
Q

In atom number of protons and electrons is the same therefore has no charge

A
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8
Q

How does an atom become a positive ion(cation)

A

Loses electrons

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9
Q

Different processes in unstable nuclei radiate different things

A
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10
Q

What is background radiation

A

Low levels of radiation that are exposed by everyday things

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11
Q

What are some sources of back ground radiation including in earth and in space

A

Earth
Nucleus power station
Medical equipment in hospitals
Buildings

Space
Sun
Cosmic rays

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12
Q

What are 2 methods of measuring radioactivity

A

Geiger Muller tube
Photographic film

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13
Q

Why will a Geiger Muller tube reading on radioactivity never be zero

A

It is always exposed to some background radiation

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14
Q

An alpha particle is the same as a _____ nucleus

A

Helium

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15
Q

What are the 2 types of beta particles

A

Beta plus-positron
Beta minus-electron

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16
Q

What is the order of these in terms of least to most ionising
Alpha beta gamma

A

Gamma-least ionising
Beta-moderate ionising
Alpha-most ionising

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17
Q

What is the order of these in terms of least to most penetrating
Alpha beta gamma

A

Alpha-least penetrating
Beta-Moderate penetrating
Gamma-most penetrating

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18
Q

How are each of these types of radiation stopped
Alpha beta gamma

A

Alpha-stopped by thing sheet of paper
Beta-stopped by 3mm of aluminium
Gamma-Very thick lead to stop it

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19
Q

JJ Thompson created the plum pudding model of the atom
What did it suggest

A

Atom made of mostly positive charge with scattered bits of smaller negative charges

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20
Q

What experiment did Ernest Rutherford do and what did it involve

A

Did the “Gold Foil Experiment”
Involved shooting alpha particles into an atom to discover the structure of it

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21
Q

In gold foil experiment most of particles went straight through ,what did this suggest

A

Most of atom was empty space
Proves JJ Thompson wrong

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22
Q

In gold foil experiment some alpha particles reflected back ,what 2 things did this suggest about the charge and structure of the atom

A

-There must be something in the centre of the atom for it to reflect back(nucleus)
-The centre of the atom had a positive charge as the alpha reflected backwards against the centre and the alpha has a porticos charge

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23
Q

What is an alpha particle made of

A

2 neutrons and 2 protons

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24
Q

What does the Bohr Model suggest

A

Most recent model
Nucleus with positive charge of protons and neutrons surrounded by shells of electrons
2 electrons in first shell
8 electrons in second and third shell

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25
How does beta minus decay happen
Neutron becomes and proton and electron and electron is ejected from nucleus at very high speeds
26
How does beta plus decay happen
Proton becomes a neutron and positron and positron is ejected from the nucleus
27
When alpha particle is emitted from an atom what happens to the elements symbol 222 Rn 86
222 4. 218 Rn —-> He. + Po 86. 2. 84 Mass (nucleon)number -4 Atomic(proton) number -2
28
When gamma is emitted from an atom what happens to it
Gamma is a wave and doesn’t change anything about the atoms atomic or mass number
29
What happens to atomic mass and number when beta minus decay happens
Atomic (proton) number +1 Mass(nucleon) number stays same Neutron changes to proton and electron and electron lost
30
What happens to atomic mass and number when beta plus decay happens
Atomic (proton)number -1 Mass(nucleon) number stays same Proton changes into neutron and positron and positron lost
31
When neutron emission happens a single neutron is lost and atomic number stays stays same and atomic mass -1
32
What is radioactive decay
When an unstable nucleus gives out radiation to become stable RANDOM PROCESS
33
What is the unit used to measure activity
Bq Becquerel
34
What is half life
Time it takes for half of undecayed nuclei to decay
35
What are some uses of radioactivity
Fire alarms -alpha Irradiating food-gamma Sterilisation-gamma Tracing and gauging thickness of materials Diagnosis and treatment of cancer
36
Lower doses of radiation can cause mutations and then divide uncontrollably
37
Higher doses of radioactivity can completely kill cells
38
Short half lives are dangerous because of high amount of radiation they release in short time but then become safe
39
Long half lives are dangerous because nearby areas are exposed to radiation for long periods of time but radiation is very small
40
What precautions are taken place for both patients and medical personnel to protect them from radiation
Limiting doses for patients Wear protective suits and distance themselves from radioactive materials
41
Objects near a radioactive source are irradiated by it Keeping sources in lead lines boxes ,standing behind barriers or being in different room are ways to reduce effects of irradiation
42
If radioactive particles get into an object the object becomes contaminated If the radioactive particles decay they will release radiation that may cause harm
43
What 2 types of emitters are usually used in internal radiation to treat tumours
Beta and alpha
44
How does internal radiation therapy work Talk about beta and alpha particles
Place alpha or beta emitter in body using implant or injecting into patient Alpha particles usually injected do lots of damage to nearby cells(cancer cells) but cannot reach to far so damage to human cells is limited Beta particles usually used in implants but can also damage human cells as they have a further penetration distance
45
Why are isotopes used to detect illnesses made close to hospital
Because they have short half life’s and if they have to go far distances their half life will be too low to use
46
Inject patient with substance containing radioactive isotope with short half life Inject into body When isotope meets cancer gamma rays are emitted and the rays are detected by pet scanner in opposite directions and show position of cancer
47
Inject patient with substance used by body The parts of body that have high metabolic activity should match where cancer cells are detected on pet scan Cancer cells divide rapidly so they will use substances quickly and will have high metabolic rate
48
What are some advantages and disadvantages of nuclear power
Disadvantages; Seen as dangerous by public Radioactive substances have very long half life’s so they could escape anew how and become a problem(Fukushima and Chernobyl) High costs Advantages; Good way of producing electricity Reduces fossil fuels Lots of energy generated
49
What is fired into uranium-235 in nuclear fission
A slow moving neutron
50
What is made after a neutron splits u-235
2 daughter nuclei are produced and 2 or more neutrons are also produced Also energy is produced and the products are radioactive
51
What is a chain reaction in Nuclear fission
When the burgeons emitted from u-235 go on to split other u-235 and goes on and on
52
How does a controlled chain reaction work
When control rods are lowered into moderator to only allow one neutron to split one u-235 at a time and absorb other neutrons
53
How does the thermal energy produced in fission produce electricity
Thermal energy is transferred to coolant of cold water Cold water is heated and turns into steam Steam turns a turbine which is connected to a generator and makes electricity
54
How is nuclear fusion different to nuclear fission
In nuclear fusion 2 smaller nuclei collide to make a larger nuclei
55
Why is some of the mass of the nuclei lost is nucleus fusion
Some of the mass is made into energy so the larger nuclei is lighter than both of the previous 2 nuclei
56
Nuclear fusion has the same process as stars use to make energy
57
Why do you need really high temperatures and pressure for nuclear fusion to happen
The charges of the nuclei will repel and to get them to join together they have to be really close to overcome strong forces of electrostatic repulsion
58
Why is the high pressures and high temperatures and nuclear fusion a problem
It is really hard to get the conditions right and very expensive
59
Alpha beta and gamma are 3 types of radioactive emission Which statement describes them all A Ionising and emitted by stable nuclei B Ionising and emitted by unstable nuclei C neutral and emitted by stable nuclei D neutral and emitted by unstable nuclei
B
60
Describe how a teacher should use a GM tube to compare count rates from 2 different radioactive rocks
-Measure count rate of area as background radiation -Take away reading of background radiation from reading of the actual rocks -Measure in same spots -Measure for same amount of time as each other
61
Carbon-14 has a half life of 5700 years The njmber of radioactive particles in it decreased from 1000000 to 125000 What is the age of the wood
1000000 +5700. 5700 time3=17100 500000 +5700 250000. +5700 125000.
62
Complete the nuclear equation 99. ___. 0 Mo—>. Tc. +. (Beta) 42. ___. -1
99. 99 0 Mo—>. Tc. +. (Beta) 42. 43 -1

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