P7 Radioactivity Flashcards
What is activity
The number of unstable atoms that decay per second in a radioactive source
What is alpha radiation ꭤ
Alpha particles, each composed of two protons and two neutrons, emitted by unstable nuclei
What is atomic number
The number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number
What is beta radiation ꞵ
Beta particles that are high energy electrons created in, and emitted from, unstable nuclei
What is chain reaction
Reactions in which one reaction causes further reactions, which in turn cause further reactions, etc.
What is count rate
The number of counts per second detected by a Geiger counter
What is gamma radiation ɣ`
Electromagnetic radiation emitted from unstable nuclei in radioactive substances
What is half-life
Average time taken for the number of nuclei of the isotope (or mass of the isotope) in a sample to halve
What is ionisation
Any process in which atoms become charged
What is meant by irradiated
An object that has been exposed to ionising radiation
What are isotopes
Atoms with the same number of protons and different numbers of neutrons
What is mass number
The number of protons in a nucleus
What is a moderator
Substance in a nuclear reactor that slows down fission neutron
what is nuclear fission
The process in which certain nuclei splitting into two fragments, releasing energy and two or three neutrons
What is a nuclear fission reactor
Reactors that release energy steadily due to the fission of a suitable isotope
