Radiation (Assessment Specific) Flashcards
Describe the structure of an atom
Positively charged nucleus with neutrons and protons. Outer shell, with electrons.
What is the size of a nucleus compared to an atom?
Nucleus is tiny compared to the whole atom.
Where is most of the mass in an atom?
In the nucleus
What are the size of small molecules when compared to an atom?
Small molecules are bigger than an atom
What is an isotope?
The Same atom, with a different number of neutrons
13
C
6
What do all these pieces mean?
13 = Neutrons + Protons = mass number 6 = Protons, usually electrons = atomic number
What can the atomic number be used to tell us?
What element it is.
What’s an easy way to tell which ones the atomic number?
The atomic number will always be smaller than the mass number
What differs between an isotope and the atom on the periodic table?
Isotopes have a different mass number
What is the charge and relative mass of a proton?
Charge + 1
Relative mass 1
What is the charge and relative mass of a neutron?
Charge 0
Relative mass 1
What is the charge and relative mass of a electron?
Charge -1
Relative mass 0
What is the charge and relative mass of a positron?
Charge +1
Relative mass 0
What is a positron?
Exactly the same as an electron but with a positive charge
What does it mean for an atom to be a neutral atom?
Number of protons = number of electrons
What does it mean for an atom to have a stable nuclei?
Balance of protons and neutrons is correct: same as atom on periodic table
How do electrons orbit the nucleus is an atom?
At different distances, first shell is different distances from nucleus in different atoms
What happens if you give energy to an electron?
It moves up one or several shells. If it gains enough, the electron will leave the atom and the atom will be a positive ion.
What happens if you take energy away from an electron?
It moves down a shell or several and emits visible light, with amount of energy dictating light colour
What is nuclear radiation?
Radiation from the nucleus
What is the symbol for alpha radiation? What is the structure of an atom emitting alpha radiation?
a, 2protons + 2neutrons
What is the symbol for beta minus radiation? What happens to an atom to cause it to release beta minus radiation?
ß-, electron emitted when a neutron turns into a proton
What is the symbol for beta plus radiation? What happens to an atom to cause it to release beta plus radiation?
ß+, proton turns into a neutron and emits a positron
What is the symbol for gamma radiation? What happens to an atom to cause it to release gamma radiation?
γ, nuclei rearrange themselves sad emit a wave of energy
What is the symbol for neutron radiation? What happens to an atom to cause it to release neutron radiation?
n, a neutron is emitted
What does all nuclear radiation do?
Ionises
What is background radiation?
The natural occurrence of radiation, present all the time
What is Radon gas produced by?
Uranium in rock decays, producing Radon gas
What are three sources of Background Radiation?
Cosmic, buildings, food, medical, nuclear power station
What two things are used to measure radioactivity?
Photographic film and Geiger counter
How does a Geiger counter detect radiation?
Inside a Geiger counter is an easily ionised gas. When gas is ionised, electrons flow. Each time the electron completes the circuit, the Geiger counter counts.
What is flow of electrons called?
Current
What is the penetration and ionisation of alpha radiation?
Penetration= 3cm through air, stopped by paper
Ionisation: highly ionising, steals 2 electrons
What is the penetration and ionisation of beta radiation?
Penetration: 2-4meters in air, stopped by thin aluminium or thick card
Ionisation: moderate
What is the penetration and ionisation of gamma radiation?
Penetration; Kilometers in air, stopped by thick lead and concrete
Ionisation; very low
What is ionisation?
Ability to take an electron from another atom
What does a billiard ball model represent an atom as?
Solid mass
What does a plum pudding model represent an atom as?
Solid with positive bits in a sea of negative
What does a Rutherford model represent an atom as?
Empty space with tiny positive nucleus and electrons around the outside
What does a bohrs model represent an atom as?
Electrons in shells around a nucleus containing neutrons and protons
Gamma radiation ionises a atom. What is the effect on the mass number and atomic number?
Everything stays the same, there’s no change
Alpha radiation particle of
4
a
2
ionises a atom of
14
C
6
What will it produce?
10
Be
4
+
4
He
2
Beta minus radiation particle of
0
Bminus
-1
ionises a atom of
14
C
6
What will it produce?
14
N
1
+
0
B
-1
Beta plus radiation particle of
0
BPlus
1
ionises a atom of
14
C
6
What will it produce?
14
B
5
+
0
B
1
Neutron radiation ionises a atom of
14
C
6
What will it produce?
13
C
6
+
1
N
0
After emitting alpha beta or neutron radiation, what may also be emitted?
Gamma
What happens to rate of decay over time?
As time goes on, activity decreases at a decreasing rate (rate it’s decreasing at gets slower
What will a half life graph look like?
It has a gentle curve of best fit
What is radioactive activity measured in?
Becquerel
Bq
What are the two ways to find half life on a graph?
Half the number of where the curve meets the y axis. Get to that number on y axis, then draw out till you meet curve. Then go down from that point, and where it lands is the half life.
Choose a number on y axis, draw out till meet curve then draw down to a point. Half the number on y axis, then draw out till meet curve then draw down to a point. Take away the smallest point number from the biggest, answer is half life.
On a half life graph, what is the y axis?
Activity
On a half life graph, what is the x axis?
Time
What is half life?
Time taken for the activity of a radioactive substance to decrease by half
Why is half life useful?
Gives us some idea of how much of the substance will be active after a period of time
The half life of carbon -14 is 5700 years. How long would it take for only 1/16th of the carbon to remain
1 1/2 ) 1/4 ) 1/8 ). 4 half lives 1/16 )
4 x 5700 = 22,800 years
Einsteinium can be produced after a nuclear bomb has been detonated. It decays to berkelium, with a half life of 20 days. How long will it take for the ratio between berkelium and einsteinium to reach 1:7
E > B 8:0 )- (Start at 8 because 7 + 1 = 8) 4:4 ) 2:6 ). 3 half life 1:7
3 x 20 = 60days
What are the dangers of being exposed to radiation?
Radiation burns, cancer and death
What are three precautions taken to ensure safety of people exposed to radiation?
Handle source with tongs, keep source in lead lined containers, do not point source at self or others, always wear gloves, wear eye protection
What is irradiation?
When someone is exposed to radiation from a nearby source
What is contamination?
When someone gets particles of a radiation source in their body
How do you stop irradiation?
Moving away from the source
How do you stop contamination?
Stops when source is finished decaying
Would gamma be more dangerous irradiating or contaminating? Why?
Irradiating as it travels long distances, contamination would move away before ionising
Would gamma be more dangerous irradiating or contaminating? Why?
Contaminating, it will ionise inside your body causing cancer or mutations
