radioactivity - 2
- Created by: Chelsey`Johnson
- Created on: 06-03-16 12:28
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- radioactivity
- ISOTOPES
- atoms or nuclei that have the same number of protons, different number of neutrons
- same chemical properties as the normal element
- BACK GROUND RADIATION
- all around us and little can be done to avoid it
- most comes from natural sources
- radon gas from the ground - makes up around half of background radiation
- buildings and the ground
- food and drink
- cosmic rays
- a small portion is from artificial sources
- mostly medicine, then nuclear power and weapons, then other sources
- GIEGER-MÜLLER TUBE
- detects ionising radiations
- tells us: the number of particles detected per second
- aka activity of the radioactive source with unit of Bequerels (Bq)
- 1Bq = 1 decay per second
- aka activity of the radioactive source with unit of Bequerels (Bq)
- if pointed at a radioactive substance for a period of time, the counter attached to it the reading would decrease
- radioactive substances can die away in micro-seconds to thousands of years
- STABLE AND UNSTABLE NUCLEI
- nucleus is unstable and will decay into a more stable atom
- this radioactive decay is spontaneous and random
- when an unstable nucleus decays, it may give out:
- alpha particle
- gamma ray
- nucleus is unstable and will decay into a more stable atom
- ALPHA PARTICLES
- charge = +2
- large charge means they are slow and heavy, and ionise other atoms strongly
- atomic mass = 4
- low penetrating power as they lose energy each time they ionise an atom
- effect of electric or magnetic field = deflection as a positive charge
- charge = +2
- BETA PARTICLES
- effect of electric or magnetic field = deflection in opposite direction to alpha
- charge = -1
- fast and light, so ionise atoms as they pass but not as strongly as alpha
- mass = 1/2000 of a proton
- medium penetrating power
- can be stopped by few cm of aluminum or plastics like perspex
- ISOTOPES
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