Radioactivity Flashcards
(14 cards)
What is nuclear fission
A type of nuclear reaction that is used to release energy from large, unstable atoms by splitting them into smaller atoms.
What is nuclear fusion
The light nuclei collide and fuse to create, heavier nucleus, some of the mass of the lighter nuclei is converted to energy and is released.
What are some risks of using radiation medically
Radiation can enter living cells, ionise atoms and molecules leading to tissue damage.
Low doses cause minor damage but can cause mutant cells to uncontrollably divide (cancer).
High doses kill cells completely, causing radiation sickness (vomiting, tiredness, hair loss) if lots of cells get hit at once.
How can radiation be used medically
Some radioactive isotopes can be injected into people and followed using an external detector showing where the strongest reading is from: they’re usually gamma emitters so it passes through the body and has a short half-life, so the radioactivity quickly leaves the person.
High doses of ionising radiation kills all living cells so it can treat cancer. Gamma rays (at the right dosage) are directed to kill the cancer cells without damaging too many normal ones, although some is inevitable.
How is background radiation caused
Radioactivity of naturally occurring unstable isotopes: in the air, food, building materials and rocks.
Radiation from space, cosmic rays are mostly from the sun is protected mainly by the atmosphere.
Human activity: fallout from nuclear waste or explosions, but this represents a small proportion of background radiation.
What are the differences between irradiation and contamination
Objects near a radioactive source are irradiated by it or exposed to it but irradiating something doesn’t make it radioactive and when working with radioactive material: lead-lined boots, barriers or remote-controlled arms can all stop irradiation.
If unwanted radioactive atoms get onto/into an object, then it’s contaminated and the atoms might decay, release radiation and cause harm. It’s dangerous as radioactive particles may get inside your body but gloves, tongs and protective suits can prevent you getting contaminated.
What is half-life
The half-life is the time taken for the number of radioactive nuclei in an isotope to half.
It can be used to predict radioactive sources despite random decay and it can also be used to find the rate at which a source decays.
How does alpha and beta decays affect the number of protons and neutrons in an atom
Alpha particles are made up of 2 protons and 2 neutrons, so when an atom emits an alpha particle, it loses 2 protons and 2 neutrons, so the charge of the nucleus decreases.
During beta decay, a neutron turns into a proton and releases an electron, so the number of protons and the number of protons and the nucleus charge increases by 1.
Alpha particles can be written as 4/2 He
Beta particles can be written as 0/-1 e
What are each types of radiation used for
Alpha: used in smoke detectors- it ionises air particles, causing a current to flow.
If there’s smoke, it binds to the ions, stopping the current and alarming sounds start.
Beta: used to test thickness of sheets of metal, as the particles aren’t immediately absorbed by the material nor are penetrated like gamma.
So, slight thickness variation affects amount of radiation to pass through
Gamma: used as a medical tracer, gamma-emitting source is injected into a patient and is followed round the body.
It’s good as it can pass out through the body to be detected.
What will alpha, beta and gamma radiation: go through, how far will they travel in the air and how ionising are they
Alpha: don’t penetrate very far, can be absorbed by a sheet of paper.
Can travel a few cm through the air.
Strongly ionising.
Beta: penetrate moderately far before colliding, absorbed aluminum sheet (5mm thick).
Can travel a few m through the air.
Moderately ionising.
Gamma: Penetrate far into materials without being stopped, absorbed by thick lead or a meter of concrete.
Can travel long distances through the air.
Weakly ionising.
What sort of process is radioactivity and what is activity measured in
Radioactive substances give out radiation from the nuclei but its decay is an entirely random process.
You can’t measure when a nuclei will decay but you can find out the time it takes for the amount of radiation to half and this is called half-life.
Half-life can be used to find the rate at which a source decays (activity) which is measure in becquerels (Bq).
What are the differences between the plum pudding model and the nuclear model and how was the nucleus discovered
The plum pudding model was a sphere of positive charge with electrons stuck in them.
The nuclear model was a positively charged nucleus with protons (and later discovered neutrons) with electrons orbiting it in shells.
Alpha particles were fired at a gold foil but some deflected back so, the scientists realised most of the atoms’ mass was concentrated in a tiny positively charged nucleus.
What are electrons, neutrons, protons, isotopes and ions
Electrons have a relative charge of -1 and orbit the nucleus in shells.
Neutrons have a relative charge of 0 and are found in the nucleus.
Protons have a relative charge of +1 and are also found in the nucleus.
Ions are charged atoms and are formed when one or more outer electrons leave or are added to the atom.
Isotopes of an element have the same number of protons but a different number of neutrons, they have the same charge but different mass.
What is the current model of the atom made up of
The nucleus is the centre of the atom, it’s tiny but makes up most of the mass of the atom.
The nucleus contains protons and neutrons and has an overall positive charge.
The rest of the atom is mostly empty space, electrons go around the nucleus in shells really fast and if they absorb EM radiation they move up to a higher energy level, further from the nucleus and if they release EM radiation, the opposite happens.
