atomic structure physics Flashcards
what is alpha radiation and how is it made?
a helium nuclei / 2 protons + 2 neutrons
when an alpha particle is emitted from the nucleus, 2 neutrons + 2 protons
what is beta radiation and how is it made?
high-speed electron
a neutron is turned into a proton and an electron
a fast moving electron is released/ ejected by the nucleus
what is gamma radiation and how is it made?
EM waves / high energy wave / high frequency / short wavelength
waves of electromagnetic radiation released by the nucleus, when nucleus changes shape
write alpha, beta and gamma in the order of starting with the most penetrating to the least
gamma (penetrate far)
beta (moderately penetrating)
alpha (doesn’t penetrate far)
what can alpha, beta and gamma be stopped by?
alpha: sheet of paper, a few cm of air, skin
beta: a sheet of aluminium, few sheets of paper
gamma: thick sheets of lead, metres of concrete
what happens when radiation ionises?
radiation ionises and that is what makes the dangerous for living organisms. It damages DNA, kills cells and causes cancer
uses of alpha, beta and gamma radiation
alpha ~ smoke alarms
beta ~ paper mills, controls thickness of paper
gamma ~ sterilising equipment
what do nuclear equations show?
radioactive decay
what is the mass and the atomic number of an alpha particle?
mass: 4
atomic number: 2
what is the mass and atomic number for beta?
mass: 0
atomic number: -1
define half life
half life is the time taken for the radioactive nuclei to decay to become stable
what is background radiation?
background radiation is the low-level radiation that is a around us all the time
what are natural sources of background radiation?
radioactive rock
cosmic rays
food + drink
what are the man-made sources of background radiation?
nuclear weapons testing
nuclear accidents
what is exposure to background radiation affected by?
occupation and location
What are doses of radiation measured in?
sieverts (Sv)
1 Sv = 1000 mSv
What does the radiation dose tell you?
Radiation dose tells you the risk of harm to the body tissues due to exposing of radiation
what is irradiation?
exposes you to radiation
what is contamination radiation?
radiation gets onto or into an object
what determines how harmful radiation is?
how far away from the source you are
how long you’re exposed
how radioactive the substance is
what are the precautions to minimise contamination?
gloves
tongs
overalls
can you emit radiation to others when exposed to radiation?
no
you can’t emit radiation to others when exposed to radiation
what is radiotherapy used for?
can be used to treat cancer
ionising radiation will kill all living cells
gamma rays are directed carefully and at just the right dosage to kill the cancer cells, without damaging too many normal cells
what are the dangers or risks of radiotherapy?
a bit of damage is inevitably done to normal cells, which makes the patient feel very ill
what are medical tracers used for?
certain radioactive isotopes can be injected into people and their progress around the body can be followed using an external detector
what are the dangers and risks of medical tracers?
risk of cancer from one use of tracer is very small
side effects
can make you feel ill
what are the ideal properties of medical tracers?
short half life ~ minimises external damage to cells
most penetrating ~ gamma (never alpha)
low ionising power ~ less damage to cells
what are the hazards of radioactive sources?
Radioactive sources can damage or cause cells to mutate when exposed + cancer
What is the instrument that measures radiation?
geiger counter
(counts the count rate)
what is nuclear fission?
the splitting of large and unstable nucleus. NOT AN ATOM!!
what is the method for nuclear fission?
a chain reaction
a neutron is absorbed by an unstable nucleus
nucleus undergoes fission splits into two smaller nuclei
this releases lots of energy and Gamma radiation
2 or 3 neutrons are also released
what process is radioactivity?
radioactivity is a totally random process meaning you can’t predict exactly which nucleus in a sample will decay next, or when one of them will decay
what are ways to reduce irradiation?
keeping sources in lead-lined boxes
standing behind barriers
being in a different room
using remote-controlled arms
what is nuclear fusion
Nuclear fusion is where two small, light nuclei collide at high speed and join together to make one heavy nucleus
define half life
half life is the time taken for a radioactive nuclei to decay and become stable
what is an isotope?
atoms with the same number of protons and electrons but have a different number of neutrons
what is ionisation?
when an atom loses or gains electrons
what is the activity of a source?
when the half-life can be used to find the rate at which a source decays - it’s ACTIVITY
