Flashcards
Radiation
Flashcards do conjunto (28)
- 1What is a radioactive substance?Radioactive substances are substances that emit radioactivity.
- 2Why are some nuclei unstable?In unstable nuclei, the strong nuclear forces do not generate enough binding energy to overcome the repulsion force inside the nucleus. Or, substances could be radioactive if the proton:neutron ratio is too big or small.
- 3An unstable nucleus becomes stable by. . .. . . emitting alpha, beta, or gamma radiation- decays. Decaying is a random event that happens with nothing being done to the nucleus
- 4What is decaying?emitting radiation.
- 5Give two properties of radioactive subtsances.1) Decaying is completely random.
2) The probability of decay is the same for each nucleus - 6What is a geiger counter and how does it workA Geiger counter is a machine used to detect radioactivity. The counter clicks each time a particle of radiation enters the tube.
- 7What was Rutherford's alpha particle scattering experiment?Rutherford's experiment involved a vacuum chamber, to prevent air molecules absorbing the alpha particles. Each time an alpha particle was shot, a small dot of light was observed.
- 8What were the results of this experiment?--> Most of the particles went straight through
--> some were partly deflected
--> very, very few were deflected at angles over 90 degrees. - 9What did the results show1) atoms are mostly empty space
2) a positive, concentrated, central, small nucleus
3) electrons are very light - 10Why was it accepted1) Rutherford + co were respected
2) it predicted the existence of the neutron
3) explained radioativity - 11what determines if a nucleus is unstable- too many protons or neutrons disturb the balance, disrupting the binding energy from the strong nuclear forces causing the nucleus to be unstable.
- 12Nuclei with atomic no above __ are radioactive83.
- 13ALPHA- same as a helium atom
- proton no goes down by 2
- mass no goes down by 4
- travels a few cms in air
- stopped by paper
- most ionizing, least penetrating
- slightly deflected in field - 14BETA- a high speed, energy electron
- mass no. of 0, atomic no. -1
- mass no doesn't change, atomic no goes up by one
- medium penetration/ionization
highly deflected in field
travels ms
stopped by aluminum - 15GAMMA- electromagnetic ray
- unlimited range of air
stopped by lead (thick)
- isn't deflected in field - 16What is background radiation?radiation from unstable nuclei in materials around us and in the atmosphere
- 17how to take background radiation into account1) measure count rate without source
2) measure count rate with source
ans to step 2) minus ans to step 1 - 18how to test different materialsplace material between Geiger Counter and source
add more layers till the count rate is 0
the radiation had been stopped - 19How to test the rangemove the source away from the tube. when the source is beyond the range of radiation, the count rate will be 0.
- 20Define ionization.when electrons are knocked out of atoms, making them have a charge, because of radiation.
- 21define irradiatedwhen an object is exposed to ionising radiation
- 22define contaminationunwanted presence of materials containing radioactive atoms on other materials
- 23how to avoid radiationkeep as far away as possible
spending little time at at-risk areas
shielding yourself with concrete barriers
long tools, special handles - 24Define peer reviewwhen findings are published and shared with other scientists so they can check them
- 25define activityThe number of unstable atoms emitted per second
or
the decay of a substance per second - 26half lifethe period of time it takes for the number of radioactive nuclui of isotops in a sample to halve.
- 27count ratenumber of counts per second
- 28count rate after N half livesInitial count rate / 2^n
Informações
- Descrição
- All about radiation except it's uses
- Criado por
- Aaishah Din
- Visualizações
- 13
- Avaliação