6.1 Radioactive Emissions Flashcards
Absorption spectrum
A continuous spectrum with dark lines corresponding to particular frequencies being absorbed by an atom
Activity
The number of decays per second
Alpha (radiation)
A particle emitted by an unstable nucleus, a helium nucleus, very ionising but not penetrating
Atomic number
The number of protons in the nucleus
Becquerel (Bq)
The unit of activity a radioactive material, equivalent to one decay per second
Beta (radiation)
A particle emitted by an unstable nucleus, a fast electron, not very ionising but quite penetrating
Energy levels (of an atom)
The allowed orbits for electrons at different distances from a nucleus
Emission spectrum
A set of frequencies of radiation emitted by an atom when excited electrons move to lower energy levels
Geiger counter
A device for measuring the activity or a radioactive material
Half-life
The time it takes for half the unstable nuclei to decay, or for the activity to halve
Ion
Charged particle formed when an atom, or group of atoms, loses or gains electrons
Ionising radiation
Particles or waves that can completely remove an electron from an atom
Isotope (of an element)
Atoms with the Same number of protons and electrons, but different numbers of neutrons, are isotopes of the same element
Mass number
The number of protons and neutrons in the nucleus of an atom
Penetrating power
The ability of radiation to travel through a material (eg. Air, metal), which is linked to ionisation
Photon
A ‘packet’ of electromagnetic radiation, how radiation is emitted or absorbed
Radiation
Anything (waves or particles) emitted from a source
Radioactive
A material containing unstable nuclei that emit radiation
Random
The nature or radioactive decay as each nucleus has fixed probability of decay
Stable (isotope)
An isotope that is not radioactive
Subatomic particles
Particles from which atoms are made, including protons, neutrons and electrons
Unstable (nucleus)
A nucleus that decays by emitting radiation or splitting (fission)
