nuclear physics Flashcards
what provided evidence for distribution of mass in an atom
The scattering of alpha particles by thin metal foil
what makes up the mass number
protons +neutron
define nuclear fission
the splitting of a large and unstable nucleus and the release of energy.
which 2 isotopes are most commonly undergo fission and are used in nuclear powerplants
uranium and plutonium
what must happen for fission to occur
uranium-235 or plutonium-239 nucleus must first absorb a neutron to make the nucleus unstable.
what happens in nuclear fission
nucleus must first absorb a neutron to make the nucleus unstable. The nucleus undergoing fission splits into two smaller nuclei, releasing two or three neutrons and energy.
which reaction (chemical or nuclear) release move energy involving a similar mass of material.
nuclear
when do chain reactions occur
A chain reaction occurs when neutrons from the fission go on to cause further fission
what do control rods in nuclear reactors do
absorb fission neutrons to ensure that on average only one neutron per fission goes on to produce further fission and energy transfer.
why is waste from nuclear reactions an issue
radioactive nature and may remain so for a long time, depending upon its half life and products
whats a factor that may influence the use of nuclear power to generate energy
The disposal of radioactive waste needs to be managed with care
define nuclear fusion
the joining of two light nuclei to form a heavier nucleus.
what happens in nuclear fusion
some of the mass of the smaller nuclei is converted into energy.
what are the conditons needed for nuclear fusion
The force of repulsion between the two positive nuclei must be overcome for them to get close and fuse and this happens at very high temperatures and pressures
how does nuclear fusion contribute to the solar system
Nuclear fusion is the process by which energy is released in stars
whats the general word equation for nuclear fusion
deterium+deterium->helium +energy
what do nuclear fission and fusion have in common
they both release energy
what is the random process od radioactive decay
some atomic nuclei are unstable. The nucleus emits particles or radiation and the nucleus changes to that of a different element and becomes more stable
define backround radiation
radioation present all around the environment
whatre the 4 natural sources of radiation
-internal from food
-building materials
-food
-soil
-gamma rays
whatre the 4 artificial sources of radiation
-medical
-nuclear weapon testing
-discharge from nuclear power plants
-air travel
what does the gieger muller tube do
detects radiation then sends implusee to counting machine when it absorbs radiation then makes a clicking sound and displays count rate
what type of radiation does the gieger muller tube measure
ioninsing radiation
whats irradiation
the process of exposing an object to ionizing radiation.
what happens when an object becomes irradiated
it doesnt become radioactive
what is contamination and why is it a hazard
the unwanted presence of radioactive atoms on other materials. The hazard from contamination is due to the decay of the contaminating atoms.
The most unstable nuclei have the ____ half-lives
shortest
whats the patern of decay
rapid and spontaneous with a lot of radiation emitted in a short time.
what is half-life
-the average time it takes for the number of nuclei of the isotope in a sample to halve
-the time it takes for the count rate from a sample containing the isotope to fall to half its initial level.
whatre the 4 things we can do to minimise irradiation
-wear gloves
-wear overalls
-use tongs to pickup material
-lead-lined boxes
