atomic structure Flashcards
what is radioactive decay
the process in which an unstable nucleus gives out radiation to become more stable
what is alpha decay and what are the properties
2 protons and 2 neutrons (He)
- can’t penetrate very far
- strongly ionising
what is beta decay and what are the properties
one of the atoms neutrons decay into a proton (stays in nucleus) and electron (which is emitted out)
- penetrate moderately far
- moderately ionising
what is gamma waves and what are the properties
waves of electromagnetic radiation
no mass and no charge
- weakly ionising
- penetrating far
explain the radiation of electrons
if the nucleus has too many neutrons it can increase the stability by getting rid of a neutron
write the equation for alpha decay of radium 226 (atomic number 88)
226 222 4
ra ——- ? + He
88 86 2
write the equation for beta decay of carbon 14 (atomic number 6)
14 14 0
C ——-? + e
6 7 -1
write the equation for gamma radiation of radium 226 (atomic number 88)
226 226
ra ——— ra + gamma decay (y)
88 88
is the decay process random or is there a specific pattern
random
what is the activity of radioactive decay
overall rate of decay of all the isotopes in our sample ( measured in Bq)
1Bq = 1 decay per second
define the two definitions of half life
- the time taken for the number of decays to half life
OR - the time taken for the number of radioactive nuclei in a sample to half
what are the steps to calculate the half life
work out how many half lives
and then half the number of radioactive nuclei that many times
the half life of a radioactive source is 40 hours, there are initially 3000000 radioactive nuclei in a sample. how many nuclei remain after five days
5 x 24 divided by 40 = 3 half lives
3000000/ 2 / 2 / 2 = 375000
what is irradiation
the process by which objects are exposed to radiation
what is contamination
when radioactive particles get onto other objects. if this radioactive material decays on you, your at risk of being irradiated
which type of radiation is most harmful and why
ionising radiation are most harmful because they can interact with molecules inside cells.
give an example of how radiation is harmful inside the body
if ionising radiation enters the cells, it can ionise DNA causing a mutation. this can cause them to divide uncontrollably possibly causing cancer
what determines how harmful radiation is
location ( inside/ outside the body), the amount of radiation (dosage), how far away from the source, how long spent near the source, how radioactive it is
what is background radiation
the radiation that is present all around in the environment
what are the sources of background radiation
rocks, cosmic rays, nuclear weapon testing, nuclear accidents
what are some uses of nuclear radiation in medicine
examining of internal organs
radiotherapy
how are gamma rays used in raditheraphy
gamma emitters direct gamma rays at the cancerous cell, these cells absorb this radiation and the die
how is beta radiation used in radiotherapy
the beta radiation is placed inside the body either next to or inside the cancerous cells in order for them to absorb the radiation and die
what are the side effects of radiotherapy
- other cells also get damaged or killed
why cancer patients feel so ill
what are medical tracers used for and how are they used
to check if organs are working properly and diagnose diseases by tracking the movement of isotopes and the radiation they emit around the body
why are gamma rays used in medical tracers and what dosage is given
they emit gamma radiation which has a shorted half life meaning radiation is only emitted for a shorter amount of time
very small dosage
what is nuclear fission and what are the two ways in which it occurs
the splitting of large and unstable nuclei into smaller nuclei
spontaneously - fission is unforced and happens by itself
absorbing a neutron - which splits a nucleus by making it even less stable
explain the process of nuclear fission using uranium 235
- start with a large unstable nuclei (uranium 235) and fire a slow moving neutron at at
- this addition of a neutron makes it even less stable and causes it to split into two smaller nuclei (daughter nuclei)
- this releases two or three more neutrons and loads of energy in the form of gamma radiation
- the neutrons are then used again to from more daughter nuclei
what are the consequences of an uncontrolled chain reaction of fission
the rate of fission is too high emitting too much energy resulting in a nuclear explosion
how can nuclear fission be controlled
- control rods - absorb neutrons - slow down reaction
- the energy released is used to heat up water, producing steam. this is then drive turbines which are connected to an electricity generator
what are the pros and cons of nuclear energy
pros - uranium is relatively cheap,
produces a large and steady amount of energy, doesn’t produce greenhouse gasses
cons -very expensive to build power plants, hard and expensive to dispose of as it has to be buried underground, risk of a major disaster if something malfunctions
what is nuclear fusion
when two smaller / lighter nuclei fuse to make a single larger nuclei
why does nuclear fusion create so much energy
some of the mass from the original smaller nuclei is converted to energy
why is nuclear fusion good and what are the issues
doesn’t produce radioactive waste
easily make hydrogen which is needed as a fuel
only happens at high pressures and temperatures
where does nuclei fusion happen and why
inside stars because of the high temperatures and pressures
