Nuclear physics Flashcards
atom
The smallest unit of an element, made from neutrons, protons and electrons.
alpha particles
A particle made from two protons and two neutrons, the same as a He nucleus, emitted as radioactive decay.
Nuclide
An atom or nucleus characterised by a specific number of protons and neutrons.
Nuclide notation
A notation using symbols for elements along with atomic number and nucleon number to describe the composition of an element’s nucleus.
periodic table (lol)
A list of the elements in ascending order of atomic number reading left to right then down the page.
proton number
The number of protons in a nucleus.
atomic number
The number of protons in a nucleus.
mass number
The total number of protons and neutrons in the nucleus, also the total relative mass of the nucleus.
nucleus
is the centre of an atom, it contains protons and neutrons.
electrons
are charged particles that orbit the nucleus.
nucleon number
is equal to the total relative mass of the nucleus.
ion
is a charged atom or particle.
isotope
is an element with a different number of neutrons to the most commonly found version.
Nuclear fusion
is the process in which light nuclei join together.
Nuclear fission
is the process in which heavy nuclei break apart.
background radiation
originates from both man-made and natural sources.
The activity of a radioactive sample is given as
count rate (counts/s).
The emission of radiation
is spontaneous and in a random direction.
The three types of decay
Alpha, beta and gamma
Radioactive decay
is a change in an unstable nucleus. The unstable nucleus emits radiation to become more stable.
Half life
is the time taken for half the nuclei to decay.
How can radioactive sources affect organisms
can damage living tissue leading to mutations, cell death and cancer. Moving and storing radioactive sources needs to be done in a way that reduces risk due to the penetrative abilities of the radiation.
Alpha ( α ) particles
An alpha particle is made up of two protons and two neutrons. The mass of each nucleon is 1, so the total mass is 4. Two protons give the α-particle a charge of +2. Due to its large mass and charge, an α particle is highly ionising.
Alpha particles are the least penetrating of all the three types of radiation. They will only travel about 5 cm through air and are stopped by materials such as thin paper or skin.
Beta ( β ) particles
A beta particle is a high-energy electron.
A β -particle has almost no mass (relative mass = 1/2000)
and a charge of –1. As a result, a β -particle does not always displace electrons from their orbit when it collides with an atom and so is only mildly ionising.
Beta particles can travel through skin but are stopped by a few millimetres of aluminium (aluminium foil).
Gamma ( γ ) emissions
Electromagnetic waves emitted by radioactive materials.
Gamma emissions have no mass and no charge, so are weakly ionising.
Gamma emissions are the most penetrating of the three types of radiation and can only be stopped by thick lead or concrete.
Penetrating abilities of radiation
Alpha particles, beta particles and gamma emissions have different properties, ionising effects and penetrating abilities.
The penetrating ability is how capable each type of radiation is of travelling through objects.
ionising affects and penetrating ability of alpha gamma and beta
alpha: High Weak
Beta: Mild Mild
Gamma: weak High
Deflecting alpha emissions
Alpha particles have a charge of +2 which means they are repelled by the positive plate and attracted to the negative plate.
Only deflected by a small amount as it has a larger mass compared to it’s charge.
Deflecting beta emissions
Beta particles have a charge of -1 which means it is attracted to the positive plate as it is deflected by the negative plate. Deflected by a large amount as it has a small mass compared to it’s charge
Deflecting gamma emissions
Gamma emissions are radioactive waves meaning they have no charge so their path is not altered of the presence of an electric field and so just travel straight through
activity
The rate at which an unstable nucleus decays
Becquerel
The unit of radioactive activity.
Bohr model
A model of the atom that suggested that electrons orbit the nucleus at set distances.
Chain reaction
The process of neutrons released by a fission reaction, being absorbed by another unstable, large nuclei, and inducing further fission.
Energy levels
The stable states in which electrons are found in around a nucleus. Electrons can transition to a higher energy level through the absorption of electromagnetic radiation and can transition to a lower energy level through the emission of electromagnetic radiation.
Fission products
Fission produces two smaller nuclei, two or three neutrons and gamma rays. All these products are released with kinetic energy.
Gamma ray
Electromagnetic radiation emitted from a nucleus. Geiger-Muller Tube: A detector that measures the count-rate of a radioactive sample.
Ions
Atoms with a resultant charge due to the loss or gain of electrons. Irradiation: The process of an object being exposed to nuclear radiation. The object doesn’t become radioactive.
isotope
Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same, but the mass number is different.
Negative ions
Atoms that gained electrons and so have a resultant negative charge.
neutrons
A neutrally charged constituent of the nucleus.
Nuclear Explosions
Nuclear explosions in nuclear weapons are caused by an uncontrolled chain reaction which results in vast quantities of energy being produced in a
very small period of time.
Plum Pudding Model
An old model of the atom that represented the atom as a ball of positive charge, with negative charges distributed throughout it.
positive ions
Atoms that have lost electrons and so have a resultant positive charge.
protons
A positively charged constituent of the nucleus.
Radioactive Contamination
The unwanted presence of radioactive atoms on other materials. It is hazardous due to the decay of the contaminating atoms.
Sieverts
: The unit used for radiation dosage.
Spontaneous fission
Fission that occurs without the absorption of a neutron. Spontaneous fission is rare and in most cases, fission is induced with a neutron.
