Nuclear Physics Details Flashcards
Structure of an atom
-Contains a positively charged nucleus(surrounded by mostly empty space)
-There are negatively charged electrons orbiting around the nucleus
Protons and neutrons are bound together by a…
strong nuclear force
Regarding mass, the nucleus contains…
most of the mass of an atom(the electrons barely have any mass)
Relative charge of protons
+1
Relative charge of electrons
-1
Relative charge of neutrons
0
Sources that significantly contribute to background radiation
-Radon gas(in the air)
-Rocks and buildings
-Food and drink
-Cosmic rays
How ionising nuclear radiation can be measured
Using a detector connected to a counter
Nature of the emission of radiation from a nucleus
Spontaneous and random in direction
Types of nuclear radiation
-Alpha particles
-Beta particles
-Gamma rays
Description of alpha particles
Each particle is 2 protons + 2 neutrons(identical to a nucleus of helium-4)
Description of beta particles
Each particle is an electron(created when the nucleus decays)
Description of gamma rays
Electromagnetic waves(similar to X-rays)
Relative charge of alpha particles
+2
Relative charge of beta particles
-1
Relative charge of gamma rays
0
Mass of alpha particles
High(compared to beta particles)
Mass of beta particles
Low
Mass of gamma rays
No mass
Speed of alpha particles
Up to 0.1× the speed of light
Speed of beta particles
Up to 0.9× the speed of light
Speed of gamma rays
Speed of light
Ionizing effect of alpha particles
Strong
Ionizing effect of gamma rays
Very weak
Ionizing effect of beta particles
Weak
Penetrating effect of alpha particles
Not very penetrating(stopped by a thick sheet of paper, or by skin, or by a few centimetres of air)
Penetrating effect of beta particles
Penetrating(stopped by a few millimetres of aluminium or other metal)
Penetrating effect of gamma rays
Very penetrating(never completely stopped, though lead and thick concrete reduce its intensity)
Effect of magnetic/electric fields on alpha particles
Deflected by magnetic and electric fields
Effect of magnetic/electric fields on beta particles
Deflected by magnetic and electric fields
Effect of magnetic/electric fields on gamma rays
Not deflected by magnetic and electric fields
Symbol for alpha particles
α
Symbol for beta particles
β–
Symbol for gamma rays
γ
(In terms of ionizing effect)The greater the charge of the radiation…
the more ionising it is
(In terms of ionizing effect)The greater the kinetic energy of the radiation…
the more ionising it is
Why isotopes of an element may be radioactive
There may be an excess of neutrons in the nucleus and/or the nucleus may be too heavy
Effect of α-decay, β-decay and γ-emissions on the nucleus
-Increase in stability
-Reduction in the number of excess electrons
What happens in alpha decay
An alpha particle(2 neutrons + 2 protons) leaves the nucleus(with 2 protons and 2 neutrons less than before)
What happens in beta decay
-A neutron in the nucleus is converted into a proton and an electron
-The electron is fired out of the nucleus whilst the proton remains
Uses of radioactive isotopes
-Household fire(smoke) alarms(Americium-241)
-Irradiating food to kill bacteria
-Sterilisation of equipment using gamma rays
-Diagnosis and treatment of cancer using gamma rays
-Tracers(iodine isotopes)
-Radioactive dating(carbon and uranium isotopes)
Effects of ionising nuclear radiation on living things
-Cell death
-Mutations
-Cancer
Safety precautions for ionising radiation
-Reducing exposure time
-Increasing distance between source and living tissue
-Using shielding(eg. lead barriers) to absorb radiation
