particle model of matter Flashcards
what is the kinetic energy within the particles
all particles move which uses kinetic energy
what is potential energy
it is the energy from inter molecular forces and bonds
what is specific heat capacity
it is the amount of energy required to raise the temperature of 1kg of a substance by 1 degree
what is specific latent heat
the specific latent heat is the amount of energy required to change the state of one kilogram of the substance with no change in the temperature
what is latent heat of fusion
the energy required to change 1kg of solid to liquid with no change in temperature
what is specific latent heat of vaporisation
the energy required to change 1kg of liquid to gas with no change in room temperature
what is the formula for energy to change state
energy to change state (J) = mass (Kg) * specific latent heat (J/Kg)
what is pressure
pressure is when gas particles exert a force on their container when colliding
what is the relation with gas pressure and volume
they are inversely proportional
what happens if an atom absorbs radiation
it moves an electron to a higher energy level which releases radiation when it moves back down an energy level
what is the atomic number
that amount of protons in an atom
what is radioactive decay
it is when an atom has an unstable nucleus so gives out radiation to become stable
what is activity of an atom
activity is the rate at which the unstable nuclei decays
what is activity measured in
becquerels (Bq)
what is the count rate
it is the number of decays each second which can be measured using a Geiger tube
what is a beta particle
it is a high speed electron fired from the nucleus at high speeds and comes from when a nucleus splits into a proton and an electron
what is a gamma ray
it is a type of radiation emitted from the nucleus
what stops each type of radiation
alpha - paper
beta - few millimeters of aluminium
several cm of lead
gamma - several cm of lead
what is the half life of a substance
the time it takes for the amount of unstable nuclei of the isotope to half or the amount of time that it takes for the count rate to fall to half its initial level
what is irradiation
exposing an object to radiation
what are the sources of background radiation
- certain rocks are radioactive such as granite
- cosmic rays through space such as supernovas
- nuclear weapons
- nuclear accidents
what is the unit for radiation
a sievert or millisieverts
what are the uses of radioactivity in medicine
- the thyroid gland absorbs iodine so radioactive iodine can be used to check its functionality
- a radioactive tracer can be used to scan the body
what are the limitations of radioactive tracers
the radiation needs to be able to be able to pass out of the body and move for a long distance in air (beta,gamma) and must not be ionising. The tracer should not decay into radioactive isotopes and must have a short half life
describe nuclear fission
one electron hits an unstable nucleus such as a uranium nucleus and it splits (undergoes nuclear fission) and releases 2 daughter nuclei (roughly the same size) and 2 or 3 neutrons and gamma radiation. this is called a chain reaction
what is nuclear fusion
when two light nuclei are joined to form a heavier nucleus so the mass of the nuclei can be converted to energy which is released as radiation and can only happen in stars
