P5 Flashcards
What is an alpha particle?
A helium nucleus
What is a beta particle?
A high energy electron
What is gamma radiation?
An electromagnetic wave
What are the properties of alpha particles?
High ionization
Low penetration
Stopped by paper
What are the properties of beta particles?
Medium ionization
Medium/low penetration
Stopped by aluminium
What are the properties of gamma radiation?
Low ionization
High penetration
Stopped by lead
How did Rutherford disprove the plum pudding model?
He sent alpha particles (which are positive) into a shin sheet of gold, and although most particles went through without changing path, some particles were rebounded hugely. This proved that there was a positively charged center of mass in the atom (the nucleus)
What is the size difference between the diameter of a atom and a nucleus?
An atom is roughly 100,000 times larger than a nucleus
When 1 beta particle is emitted, what is the effect on the atomic number?
It will increase 1
When 1 beta particle is emitted, what is the effect on the atomic mass?
There is no effect
When 1 neutron is emitted, what is the effect on the atomic number?
There is no effect
When 1 neutron is emitted, what is the effect on the atomic mass?
It will decrease by 1
What is an isotope?
An element with a different number of neutrons, but the same amount of protons and electrons
What is the half-life of a source?
The time it takes for activity to halve from its original value
What is irradiation?
When an object is exposed to radiation
What is contamination?
When a radioactive source is in or on an object, therefore the object becomes a source
What can high doses of radiation do?
Kill cells completely
What can low doses of radiation do?
Cause cell mutations which can lead to cancer
How damaging is gamma waves outside the body?
Gamma are dangerous outside the body as they can penetrate very far into the body and get to delicate organs
How damaging is gamma waves inside the body?
Gamma rays are not dangerous inside the body, as due to their high penetration, most of the radiation just passes through without doing any damage
How damaging is alpha particles outside the body?
Alpha particles are not dangerous outside the body, as due to their low penetration, they cannot penetrate the skin, preventing them from causing any harm
How damaging is alpha particles inside the body?
Alpha particles are very dangerous inside the body, as they do all their damage in a very localised area, likely causing cell destruction
How damaging is beta particles outside the body?
Beta particles are fairly dangerous outside the body, as they can penetrate the body and therefore cause damage, just not as much as gamma waves
How damaging is beta particles inside the body?
Beta particles are less damaging than alpha inside the body, as they do their damage over a wider area, and some particles pass out completely
What do tracers do?
They see if parts of the body are working
What radiation do tracers use and why?
They use gamma sources with a short half-life, as gamma can penetrate through the body and be detected by the sensors without causing much damage
How are tracers taken into the body?
They are injected or ingested
How do we treat cancer externally?
A beam of gamma rays are fired at the tumour, in the hope it will kill the cancer cells
How do we treat cancer internally?
Implants containing beta or alpha emitters are placed in or next to a tumour, in the hope they will kill the cancer cells
Why do we use beta or alpha emitters in implants?
They can damage the cancer cells, however have a short range so healthy cell damage is limited
What do we have to do to long half-life implants?
We must remove them to stop them killing more healthy cells after the cancerous cells have been killed
What do we have to do to short half-life implants?
Nothing- we can leave them in there as their activity will fade away quick enough so as to not cause further healthy cell damage
What is activity measured in?
Bq
Describe the process of nuclear fission
1) A large unstable nucleus absorbs a neutron, causing it to split into 2 smaller nuclei
2) This change gives out a lot of energy
3) Each time a nucleus splits, some neutrons are also spat out
4) Each of these neutrons has the ability to cause another nuclei split and so on and so on
5) This is called a chain reaction
What do 2 hydrogen nuclei form when fused together?
A helium nucleus
Where is the energy produced from in fusion?
The change in mass between the original and new nucleus is converted into energy and carried away by radiation
What are the pros of nuclear energy?
No greenhouse gases Low operating costs Reliable Efficient Possibly renewable in the future
What are the cons of nuclear energy?
Environmental impact Difficult waste disposal Nuclear accident risk Expensive to set up Target for militants Right now, non-renewable
