Atomic Structure: Radiation Flashcards
Describe the structure of alpha particles.
- a helium nucleus
- consists of 2 protons and 2 neutrons
Describe the structure of beta particles.
- a beta particle is an electron
- a beta particle comes from the nucleus
Beta particles
- range in air
- penetrating power
- ionising power
- around 15cm
- stopped by a few mm of aluminium
- quite strongly ionising
Describe the structure of gamma radiation.
They are a type of electromagnetic wave and not particles.
Gamma Radiation
- range air
- penetrating power
- ionising power
- several metres
- stopped by several cm of lead
- weakly ionising
Describe the structure of alpha particles.
- consist of 2 protons and 2 neutrons
- a helium nucleus
Alpha particles
- range in air
- penetrating power
- ionising power
- few cm (around 5cm)
- stopped by a single sheet of paper
- very strongly ionising
What are the two definitions of half-life?
The half life of a radioactive isotope is the time it takes for the number of nuclei of the isotope in sample to halve
The half-life is also the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level.
What is irradiation?
Exposing an object to nuclear radiation. The object does not come into contact with the radioactive source however so does not emit radiation.
What is radioactive contamination? What effect does it have?
When unwanted radioactive isotopes end up on other materials. This is hazardous as the radioactive atoms emit radiation.
Evaluate the dangers of alpha radiation.
- strongly ionising
- easily stopped by dead cells on the skin surface
- very dangerous if inhaled or swallowed as they cannot leave the body
Evaluate the dangers of beta radiation.
- quite ionising
- can penetrate skin into the body where they can damage cells
Evaluate the dangers of gamma radiation.
- weakly ionising
- can penetrate body but likely to pass straight through
What is count rate?
The number of decays that a detector measures per second.
