Unit 7 - Radioactivity Flashcards
define contamination
non radioactive material gets in contact with radioactive material
(radioactive material must get in touch)
define irradiation
Exposure to nuclear radiation. The irradiation stops when
the source is removed or blocked.
describe the nature of an alpha particle meaning physical representation
2 protons 2 neutrons
helium nucleus
describe the nature of a beta particle
electron
describe the nature of a gamma particle
electromagnetic wave
in practice question- explain why fruits irradiated with amma radiation are safe to eat
- fruits are not radioactive
- fruits are not in contact with radioactive source
- fruits are not contaminated
what is meant by nucleon number / mass number
the protons + the neutrons in the nucleus of an atom
imp question- define isotopes
isotopes have the same atomic number but different mass number`
define ioniasation
removal of electrons from an atom
what is meant by alpha decay
the emision of an alpha particle from an unstable nucleus
define radioactivity
The production of ions by radioactivity due to the energy transferred
what is meant by atomic number or proton number
The number of protons in the nucleus of an
atom
what is background radiation
The nuclear radiation from natural and artificial sources in our everyday environment
name some sources of background radiation
- building rays
- cosmic rays (from stars)
- hospitals
- radon gas from the earth
define half-life
time taken for a sample of radioactive material to have half of its atoms decayed
what is the charge of an alpha particle
+2
what is the charge of a beta particle
-1
what is the charge of a gamma
neutral as it is a wave
describe the penetration abilities of alpha
very low penetration ability
can be stopped by a sheet of paper
describe the penetration abilities of beta
stronger penetration compared to alpha
can be stopped by 3mm of Al sheet
describe the penetration abilities of gamma
very strong penetration ( more than alpha and beta)
can be stopped by several meters of concrete / which will absorb more gamma ray
name a device used to detect radiation
GM tube
explain the condition needed for nucleur fission
- high temperature required
- to increase KE of nuclei
- high pressure required
- because nuclei need to be close enough to collide
- since nuclei repel each other so to overcome the electrostatic forces of repulsion
the energy released by the fision process starts in the nuclear store of the uranium atom. describe the transfers that occur after that
- nuclear store of uranium
- KE store of fision products
- thermal store of graphite a gas
- thermal store of water
- KE of turbine
- electricity by generator
how is boron used in a nuclear reactor
control rod
what does a control rod do
absorb neutrons and stop chain reaction
use of uranium in nuclear reactor
fuel rod
function of fuel rol
provide nuclei for fision reaction
use of concrete / lead in nuclear reactor
sheilding
contains water that absorb neutrons ( for safety )
what is grpahite used for in nuclear reactor
moderator
function of moderator
slow down the fast neutrons from one fision reaction so they can be absorbed
explain why background radiation is not always the same
radiation is random
define chain reaction
When neutrons from the fission of one uranium nucleus are allowed to cause fission in more uranium nuclei, which
release more neutrons to continue the process
