nuclear physics ☢️ Flashcards
What are isotopes
atoms of the same element that have the same proton number but different nucleon number.
What are nucleons
Protons and Neutrons.
What force binds the protons and neutrons together
“Strong Nuclear force”
When does a nucleus disintegrate
When it is unstable
When is a nucleus considered unstable
When the atom has extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced or unstable.
What does it mean for nucleus to disintegrate
The nucleus breaks up and radiates a tiny particle in order to achieve stability
What does it mean for a material to be radioactive
The material emits nuclear radiation
What is the meaning of “radioactive decay”
Disintegrations of a heavy nucleus which is random and spontaneous. They can result in the emission of α-particles or β-particles and/or γ-radiation.
What does it mean to have an ionizing effect
Ability to remove electrons from atoms in its path. This makes all the atoms in its path ions
What are the 3 types of radiation
Alpha
Beta
Gamma
What is each radiation stopped by
Alpha - 1 sheet of paper
beta - A sheet of aluminium
gamma - 2 cm or more of lead/thick lead/50 cm of concrete (reduces intensity not fully stop)
Speed of 3 radiations
Alpha - slowest of 3 = 0.1 * c
beta - faster than alpha, slower than gamma = 0.9 * c
gamma - fastest = c
Mass of 3 radiations
Alpha - heaviest
beta - lighter than alpha, heavier than gamma
gamma - none
Relative charges and ionizing powers of 3 radiations
Alpha = +2, strong ionizing
Beta = -1, weak ionizing
gamma = 0, very weak ionizing
Effects of electromagnetic fields on 3 radiation
Alpha and beta - deflected by magnetic and electric fields
Gamma - Not deflected by any fields
What are alpha particles made off
2 protons, 2 neutrons.
Similar structure to nucleus of helium
What are beta particles made off
Each particle is an electron
What are gamma particles made off
Electromagnetic waves similar to X rays
Why are alpha and beta particles deflected in fields
in a magnetic field -
in an electric field -
which gets deflected more in both and which diretion
Alpha beam - flow of positively charged particles (same flow as current)
Beta particles - electrons (flow opp to current)
In a magnetic field - both follow flemings left hand rule
In an electric field - if they pass 2 oppositely charged plates, they experience a force
Beta particles deflected more in both since its lighter but in the opposite direction to alpha particles since charges are opposite
how can the deflection of alpha and beta rays in magnetic fields be found?
alpha particles are heavy and a flow of positively charged particles, so it is equivalent to an electric current, hence we can use Flemings’ left-hand rule to find the direction of deflection. As it is heavy it is deflected less
(since its positive, its the same direction as conventional current hence alpha is left hand rule and beta is the opp of wtv alpa is)
beta particles are much lighter and are a flow of negatively charged particles so it is equivalent to an electron flowing in a magnetic field, which is the opposite direction of the current flow. As it is light it deflects more
background radiation definition
Background radiation is the radiation that is present all around in the environment
what are the factors that make a significant contribution to background radiation
radon gas (in the air)
rocks and buildings
food and drink
cosmic rays
how is a Geiger muller tube used to detect alpha particles
if an alpha particle enters the tube, sparks are produced towards the negative plate and a big and loud sound is created
how is a Geiger muller tube used to detect beta particles
if a beta particle enters the tube, sparks are produced towards the positive plate, this spark is fast and a low sound is produced
how is a Geiger muller tube used to detect gamma particles
if a gamma particle enters the tube, trail of sparks, no sound and no deflection occurs
what are the 3 possible apparatuses a GM tube can be connected to
what does each do
ratemeter - How many of that radiations particles are detected per second. Eg: 100 alpha particles detected per second so the reading is 100 counts per second.
scaler - total number of particles detected by the GM tube
amplifier and loudspeaker - makes a ‘click’ sound when a particle or burst of gamma radiation is detected
what is a corrected count rate
the count rate subtracted by the background radiation count
properties of alpha decay
decreases the mass number by 4
atomic number decreases by 2
doesn’t form isotopes but rather a new element altogether
produces a helium atom
eg: parent nuclei —> parent nuclei (mass no -4, proton no -2) + helium (mass no 4, proton no 2)
properties of beta decay
beta particles breakdown a neutron into 3 parts
proton
electron
antineutrino (fast moving massless, chargeless particle)
no change in the mass number since one neutron gets converted to one proton
beta proton number decreases by 1
the atoms proton number increases by 1
what kind of particle is an alpha, gama and beta
gamma is electromagnetic
beta is electron
alpha is a helium nucleus
How does risk of exposure to radiation vary
Greater the intensity of the radiation and longer the exposure the greater the risk
Effects of ionising nuclear radiations on living things
Mutations - Changes in genetic instructions which may grow abnormally and cause cancer
cell death
Which radiation is most harmful and why
Alpha radiation - highest ionizing power
Which radiations are potentially harmful to internal organs and which arent.
Harmful - beta and gamma because they can penetrate through to the internal organs.
Not harmful - Alpha particles. They can’t penetrate the skin and hence can’t reach the internal organs.
Why is radioactive gas and dust especially harmful
They are taken in the body with air, food and drinks
Give an equation in terms of parent nucleus, daughter nucleus and decay products.
Parent nucleus —> daughter nucleus + decay products
What happens when an unstable nucleus undergoes Alpha decay
Original isotope loses 2 protons and 2 neutrons
What happens when a particle undergoes beta decay
A neutron becomes a proton
An electron and an anti-neutrino is given out
What happens in gamma emission
When beta or alpha decay take place, protons and neutrons rearrange themselves to become more stable. They lose energy when they do this. That lost energy is emitted as a burst of gamma radiation
What is a half-life of a particular isotope
time taken for half the nuclei of that isotope in any sample to decay
What is activity
What is the unit
Average number of disintegrations per second is known as the activity
Unit: Becquerel (Bq)
What is the stability line
What is above the stability line? What happens
What is below the stability line? What happens
what happens to the heaviest isotopes
Stable isotopes lie on the stability line
Isotopes above the stability line have too many neutrons to be stable. They undergo beta- (electron) decay to reduce the number of neutrons.
Isotopes below the stability line have too few neutrons to be stable. They undergo beta+ (positron) decay to increase the number of neutrons.
Heaviest isotopes decay by alpha emission.
In a cathode-ray tube, a hot tungsten cathode releases particles by thermionic emission.
What are these particles?
electrons
a radioactive nucleus emits a beta particle
what happens to the proton number of the nucleus of the atom
proton number increases by 1
what is always a product of nuclear fission
neutron
How many isotopes can an atom have
more than one
In which decay does the nucleus change to a diff element
α-decay or β-decay
2 economic issues involved in the storage of radioactive materials with very long half-lives
high cost of storage/shielding/guarding/ need to store for a long time
OR reduction in tourism
OR loss of farming produce/land
OR reduction of land/property values
2 social issues involved in the storage of radioactive materials with very long half-lives
fear of cancer/ causes cancer/genetic mutations/radiation sickness in people/ animals
OR local objections
OR cause people to move away
2 environmental issues involved in the storage of radioactive materials with very long half-lives
crop mutations
OR leakage into water supplies
OR pollution of atmosphere/water supply
Why are alpha particles more stongly ionising than beta particles
larger charge (+2 vs -1)
slower moving
more massive/greater volume/ more chance of collision
