Topic 6-Radioactivity Flashcards
What was Thompson’s model called and what was it?
The plum pudding model. Postively charged material with negative electrons scattered through it.
What did Rutherford suggest?
Rutherford suggested that atoms were mostly empty space with most of the mass in a tiny central nucleus with a positive charge and electrons moving around the nucleus.
What is ionising radiation?
When an atom gains so much energy one of the electrons jumps to a higher orbit and escapes due to radiation. When an atom gains or loses an electron it is an ion.
What is backround radiation?
Radiation that is around us at all times at a safe level(radiation is measured in Benquerels or counts per minute).
What are some of the sources of backround radiation?
radon gas 49-rocks that contain uranium
food and drink 10
cosmic rays 10
medical 15
What are cosmic rays?
Charged particles from stars.
How can radioactivity be measured?
Using photographic film which darkens or with a geiger muller tube and counter. Newer dosmimters change colour without needing to be developed.
How do geiger muller tubes work?
Radiation ionises gas inside it and creates a pulse of current.
What are alpha particles?
Helium nucleus(2p 2n)-most ionising but least penetrative.
What are gamma rays?
EM radiation-energy instead of particles like other two-most penetrative but least ionising.
What are beta particles?
High speed, high energy electrons that have been emited from radiation
What is a positron emission? b+ decay.
When a proton goes to a neutron and a positron.
What is a neutron emission?
This is just when a neutron leaves.
Why do atoms decay?
To become more stable.
What is b- decay?
A neutron changes into a proton and an electron.
What is a half life?
Time it takes for radioactivity to half.
How can radiation be used to kill microorganisms?
Food can be irradiated or surgical instruments taht would melt if heated(plastic) can be sterilised.
How can radiactive tracers be used for water pipes?
A gamma source can be added to water pipes so when it leaks a geiger muller tube can be used above the ground to detect leaks.
How can radiation be used to check for thickness?
How can radiation be used in smoke alarms?
What are the dangers of radioactivity?
It can cause cancer.
What is contamination?
If an object has a radioactive material introduced into it(somethething inside).
Whatis irradiation?
Exposing objects to beams of radiation is called irradiation(going through something from outside).
How can you diagnose with positrons?
Tracers that emit positrons can be put into the body as when they meet with an electron theyare destroyed and release 2 gamma rays. The detector in a PET scan will see this.
