Radioactivity Flashcards
Define ‘radiation’
Transmission of radiant energy
Define ‘radioactivity’
Spontaneous emission of radiation from an atom, in order to form a more stable configuration
Define ‘isotope’ (of an element)
An atom with the same atomic number (Z) of the given element, but different mass number (A)/number of neutrons
Define ‘half-life’
The time taken for the activity of a radioactive substance to fall by half
Describe alpha decay and its effects on an atom
Alpha decay is the emission of a helium nucleus (2 protons and 4 neutrons) by a radioactive atom
It decreases the atomic number (Z) by 2 and mass number (A) by 4
Describe positron emission and its effects on an atom
Positron emission is the emission of the positively charged component of a proton (positron) to form a neutron
This decreases atomic number (Z) by 1, but mass number (A) remains unchanged
Describe beta decay and its effect on an atom
Beta decay is the emission of a negatively charged electron from a neutron to form a proton
This increases the atomic number (Z) by 1, whilst the mass number (A) is unaffected.
What conditions cause positron emission?
A neutron deficit, to create more neutrons to compensate
What conditions causes beta decay?
A neutron abundance, to decrease the number of neutrons in the nucleus
When does gamma decay occur?
Gamma rays are released due to a nucleus being in a metastable state and are emitted stablise it.
They’re usually released as a result of other radioactive decay too.
Describe gamma decay and its effect on an atom
A gamma ray photon is emitted to release energy from an excited nucleus (metastable). No particles are emitted so the atomic make-up is unaffected.
A carbon (Z=6, A=12) atom undergoes alpha decay - what is the result?
A new atom with Z=4 and A=8 is created (Berylium)
An oxygen atom (Z=8, A=16) undergoes alpha decay - what is the result?
A new atom with Z=6 and A=12) is created (Carbon)
What constitutes ‘ionising’ radiation?
Ionising radiation has enough energy to eject an electron from a target, resulting in ion formation
Name 3 natural sources of radiation, with examples
Cosmic Radiation - solar flares from the sun
Terrastial radiation - radiation from radon, granite and uranium
Internal - ingested radiation from bananas, brazil nuts and carbon-14
