Radioactivity and Particles - Radioactivity Flashcards
what are atoms made up of?
protons, neutrons and electrons - protons and neutrons are in the nucleus, electrons are in the shells
what is atomic number?
the number of protons in the nucleus of an atom
what is mass number?
the total number of protons and neutrons in the nucleus of an atom
what is an isotope?
an atom of the same element, but has a different number of neutrons/different mass number
what are the 3 types of ionising radiation?
Alpha (α), Beta (β) and Gamma (γ)
what is ionisation?
when an atom loses or gains an electron, causing it to become an ion (an atom which is positively or negatively charged)
what is the ionising power and range in air of alpha particles?
- strong ionising power
- a few cm range
- stopped by paper
what is the ionising power and range in air of beta particles?
- moderate ionising power
- 1m range
- stopped by aluminium
what is the ionising power and range in air of gamma particles?
- very weak ionising power
- atleast 1km range
- stopped by lead
how would you investigate the penetration powers of different types of radiation?
- detect using a Geiger Müller Tube
- first note the measurement without any sources (CMBR)
- try the three different materials in order: paper, aluminium then lead.
- the count rate will significantly decrease if radiation is stopped
what are the effects of alpha decay on the atomic and mass numbers of a nucleus?
- 2 protons and 2 neutrons are lost
- mass number decreases by 4
- atomic number decreases by 2
what are the effects of beta decay on the atomic and mass numbers of a nucleus?
- 1 neutron is converted to an electron (lost from the atom) and proton
- mass number is unchanged
- atomic number increases by 1
what are the effects of gamma decay on the atomic and mass numbers of a nucleus?
- energy is lost from an atom in the form of an electromagnetic wave
- mass number is unchanged
- atomic number is unchanged
what can detect ionising radiations?
photographic film or a Geiger−Müller detector
- when connected to a counter, the detector will be able to measure radioactivity
- radiation will cause photographic film to darken
what are the sources of background radiation?
- radon in the air
- granite in rocks
- cosmic rays
- medical equipment
- food and drink
what happens to the activity of a radioactive source over time?
the activity of a radioactive source decreases over a period of time
what is the activity of a radioactive source measured in?
becquerels
what is half-life?
the half-life is the time taken for the radioactivity of a specific isotope to fall to half its original value
how is gamma used as a medical tracer?
- radioactive tracer put in body (swallowed/injected)
- detector put around body
- computer generates an image
how is gamma used in radiotherapy?
- high doses of radiation are directed at cancer cells
- cancer cells are killed
how is gamma used as a pipe tracer?
- a radioactive material which emits gamma radiation with a short half-life is put in the water
- a detector is placed above the pipe
- a spike in detected radioactivity suggests a leak in the pipe
how is gamma used in sterilisation?
- medical equipment irradiated
- kills all living matter on tools (e.g. bacteria)
what is contamination?
contamination occurs when material that contains radioactive atoms is deposited on materials
what is irradiation?
the process by which an object is exposed to radiation
what are the dangers of ionising radiation?
- can cause cell mutation/death
- can damage tissue
- hard to dispose of (needs to be in a secure area and in multiple lead-lined boxes)
how can you reduce the risk of ionising radiation?
- keep sources away from the body
- wear gloves when handling
- minimise time spent in areas with high radiation
