Topic 6) Radioactive decay Flashcards
what is the ionising radiation that we are exposed to?
background radiation
what is the biggest source of background radiation?
uranium
where is uranium produced?
magnesium rocks
what is the background radiation that comes from space called?
cosmic radiation
what is reason an atom’s nucleus is stable?
only if it has a full outer shell
what happens if a nucleus has too many, or too few neutrons?
becomes unstable and will decay, and emit radiation
what are the different types of radiation?
alpha
beta
gamma ray
what is the relative mass of alpha particles?
4
what is the charge of a beta particle?
-1
what is the particle that has no mass or charge?
alpha particle
what has a high frequency?
gamma ray
what is a type of electromagnetic radiation?
gamma ray
which particle has an electron from the nucleus?
beta
what is the charge of a gamma ray?
+2
what happens during beta emission?
A neutron turns into a proton and creates an electron
What happens during positron emission?
A proton turns into a neutron and a positron is created
What happens during neutron emission?
A neutron is lost from the nucleus
What 3 isotopes can hydrogen exist in?
Protium
Deuterium
Tritium
What can gamma particles be stopped by?
A few centimetres of lead or concrete
What can stop beta particles?
Aluminium
how can radiation be used to setrilise food?
kills cells, so it’ll kill all microbes on the food
what is the symbol for electric charge?
Q
what is charge measured in?
coulombs
what is charge carried by in an electric circuit?
free,or de-localised electrons
What do alpha particles contain?
Contains 2 protons and 2 neutrons
what levels of energy do beta particles have?
high energy
what levels of speed of beta particles have?
high speed
what is the relative mass of beta particles?
1/1835
what are gamma-rays?
they are high-frequency electromagnetic waves
what do gamma waves travel like?
gamma rays travel at the speed of light
what is the electric charge of gamma rays?
they do not have a electric charge
what are the characteristics of alpha particles?
will travel a few centimetres in air
very ionising
can be stopped by a sheet of paper
what are the characteristics of beta particles?
will travel a few metres in air
moderately ionising
can be stopped by a 3 mm thin aluminium
what are the characteristics of gamma rays?
will travel a few kilometres in air
weakly ionising
need thick lead or several metres of concrete to stop them
what materials stop alpha particles?
paper
what materials stop beta particles?
aluminium 3 mm thick
what materials stop gamma rays?
lead few cm thick or several metres of concrete
what is used to measure radiation?
A Geiger Counter
what is the pressure in the Geiger counter?
low pressure gas
what nucleus is an alpha particle?
a helium nucleus
what type of electron is a beta particle?
a high speed electron
what is the ionising power of an alpha particle?
high
what is ionising power of a beta particle?
low
what is the ionising power of a gamma particle?
very low
what can detect radioactive decay?
photographic film
what can be predicted about radioactive decay?
the number of nuclei that will decay
what is half life?
the time taken for half of the unstable nuclei in a sample to decay, or for the activity of the sample to halve or for the count rate to halve
what is the geiger-muller tube?
a device that detects radiation
how does a geiger-muller tube work?
it gives an electrical signal each time radiation detected
these signals can be converted into clicking sounds, giving a count rate in clicks per seconds or per minute
what is radioactive substance measured in?
becquerel (Bq)
what does alpha decay do?
changes the mass number of the element by minus four and the atomic number by minus two
what does beta decay do?
changes the atomic number by plus one but the mass number remains unchanged
