radioactivity Flashcards
what is the structure of an atom?
a positively charged nucleus which contains positive protons and neutral neutrons, negatively charged electrons on the outer shells
what are the masses and charges of these:
- proton:
- neutron:
- electron:
proton: mass= 1 charge= +1
neutron: mass= 1 charge= 0
electron: mass= 1/1826 charge= -1
what is an isotope?
atom with the same number of protons, but different number of neutrons
when electrons move to a higher orbit (away from the nucleus), what happens to the EM radiation?
the atom absorbs the EM radiation
when electrons move to a lower orbit (closer to the nucleus), what happens to the EM radiation?
the atom emits EM radiation
what are the 4 forms of decay?
- alpha
- beta minus
- beta plus
- gamma
how ionising are these?
- alpha
- beta minus
- beta plus
- gamma
- alpha: highly ionising
- beta minus: medium ionising
- beta plus: medium ionising
- gamma: low ionising
how penetrating (able to get through things) are these?
- alpha
- beta minus
- beta plus
- gamma
- alpha: weakly penetrating
- beta minus: medium penetrating
- beta plus: medium penetrating
- gamma: highly penetrating
what are 3 examples of background radiation?
- cosmic rays
- medical rays
- radiation from underground rocks
what is one way of measuring radioactivity and how is it used?
geiger-muller tube, a tube that can detect radiation, it absorbs radiation and transmits an electrical pulse to the machine creating a clicking sound, the more clicks the more radiation present
what did Dalton say about atoms?
he said everything is made of atoms
what did jj thomson discover and what model did he form?
he discovered the electron and made the plum pudding model
what is the theory of the plum pudding model?
jj thompson said the overall charge of an atom is neutral so he created a circle of positive charge and placed negative electrons on it
what did Rutherford realise and what experiment did he use?
he realised most of the atom is empty space and he used the gold foil experiment
what is the Rutherford model?
there is a positive nucleus in the centre of an atom and the electrons are distributed in the space around the nucleus
who produced the final model of the atom and what is it?
Bohr produced the final model and he concluded that the electrons exist in fixed orbits around the nucleus
what is half life?
the time taken for half the nuclei to decay
what are 3 uses of radioactivity?
- smoke alarms
- diagnosis/treatment of cancer
- sterilise equipment
what safety precautions do medical doctors need to take when undergoing radioactive tests?
they should leave the room as it puts their health at risk in the long term
what are the two ways radiation can treat tumours ?
external and internal
what is the external treatment of tumours and how effective is it?
where a beam of gamma radiation rotates around the body, mainly focuses on the tumour but can sometimes pass the healthy cells
effectiveness: takes a long time to fully treat the tumour, greater risk of long term side effects as radiation passes through healthy cells
what is the internal treatment of tumours and how effective is it?
patient injected with radioactive material directly onto the tumour
effectiveness: doesn’t affect the healthy cells around, however a long time is to be spent in hospital as the patient will have high radioactivity and can emit radiation so limited contact is to be made
how do PET scanners work?
- a radioactive tracer is inserted into the body
- the scanner records where the tracer emits radiation
- this produces an image of the body
what are PET scanners used for?
- they are used to show how effective treatment is
- to diagnose cancer
