Radioactivity Flashcards
Beta Minus decay
A neutron becomes a proton and the atom releases and electron
Beta Plus decay
A proton becomes a neutron and the atom releases a positron
Alpha
An alpha particle is the equivalent to a helium nucleus
Beta
A beta particle is an electron emitted from the nuclear
Half life
Half life of and isotope is the time taken for half the nuclei in a sample to decay
use of radioactivity
- smoke alarms
- sterilisation of equipment
- tracing and gauging thickness
- diagnosis and treatment of cancer
- Irradiating food
What year did dalton say everything was made of atoms ?
1800
What year did JJ Thomson discovered the electron?
1897
What is the plum pudding model ?
The idea that the overall charge of an atom is neutral, so the negative electrons are dispersed through the positive pudding so the charges cancel out
What year did Rutherford realise most of the atom was empty space ?
1911
Who created the gold foil Experiment?
Hans Geiger and Ernest Marsden
What is background radiation?
Radiation that is always present
What is a source of background radiation ?
Nuclear weapon testing
How do measure background radiation?
Geiger Müller counter or a photographic film
How does the Geiger muller tube work ?
What the tube absorbs radiation it produces a pulse which is counted to count the amounts of radiation
What will block beta radiation?
A thin sheet of aluminium
What will block gamma radiation?
Several centimetres of lead
What type of radiation is most ionising ?
Alpha
Which type of radiation is least ionising?
Gamma
What is the step to Rutherford model ?
- Alpha particles were fired at a sheet of gold metal
- most particles went straight through
- Some particles were deflected
What happens to an atom when alpha decay occurs ?
The atomic number decreases by 2
The mass number decreases by 4
What does beta minus decay do to the atomic mass and number of an atom ?
The mass number stays unchanged
The atomic number increases by 1
What are some examples of radioactivity uses ?
Smoke alarms
Irradiated food
Sterilisation of equipment
Treating and diagnosing cancer
How do the smoke alarm work ?
- The radioactive substance in the alarm emits alpha radiation
- The alpha particles ionises the air in the detector (causing a current between plates)
- When smoke interferes with the radiation the air is no longer ionised (the current between plates stop)
- The reduction of flow triggers alarm
What are 2 uses of nuclear radiation in the field of medicine ?
Examining internal organs and treatment of cancer
Why is ionising radiation dangerous
It can cause cell mutation
What precautions should people take when using ionising radiation?
Avoid handling the source directly
Wear radiation protection clothing
Use lead containers to reduce radiation escape
How is a radioactive tracer used in medicine ?
- The tracer is injected into the body
- The tracer releases gamma radiation which is detected by a detector
- The can be used to cheat a picture of patient body
