Atomic physics Flashcards
Describe the structure of an atom
Positively charged nucleus surrounded by negatively charged electrons
Describe how the scattering of α-particles by thin metal foils provides evidence for the nuclear atom
- Majority of them go straight through
- Some are slightly deflected
- Very few are deflected straight back
Which experiment investigates the scattering of α-particles?
Rutherford’s gold foil experiment
What is the nucleon number also referred to as?
Mass number
What is the proton number also referred to as?
Atomic number
What is meant by the term nuclide?
A nucleus with a specific combination of protons and neutrons
What is an isotope?
Atoms of the same elements with the same number of protons but different number of neutrons
What is nuclear fission?
The splitting of nuclei to release energy
What is nuclear fusion?
The joining of nuclei to release energy
What is background radiation?
Radiation that is always present around us in the environment
What is an artificial source of background radiation?
X-rays used in medical procedures
How do radiation detectors work?
Detect the presence of ions or the chemical changes they produce
What are 5 examples of radiation detectors?
- Photographic film
- Geiger-Muller (GM) tubes
- Ionisation chambers
- Scintillation chambers
- Spark chambers
What are 3 types of radiation?
- Alpha particles
- Beta particles
- Gamma rays
What is the nature of alpha particle emissions?
High energy
What is the nature of beta particle emissions?
High energy
What is the nature of gamma ray emissions?
High energy electromagnetic waves
What is the ionising effect of an alpha particle?
Very strong
What is the ionising effect of a beta particle?
Weak
What is the ionising effect of a gamma ray?
Very weak
What is the relative penetrating ability of an alpha particle?
Stopped by paper
What is the relative penetrating ability of a beta particle?
Stopped by a few mm of aluminium
What is the relative penetrating ability of a gamma ray?
Only reduced by lead
Describe the deflection of alpha particles in a magnetic field
Slightly deflected
Describe the deflection of beta particles in a magnetic field
Greatly deflected
Describe the deflection of gamma rays in a magnetic field
No deflection
Describe the deflection of alpha particles in an electric field
Slightly deflected
Describe the deflection of beta particles in an electric field
Greatly deflected
Describe the deflection of gamma rays in an electric field
No deflection
Why are alpha and beta particles ionising?
They are charged
What is a natural source of background radiation?
Underground rocks
Why are beta particles deflected more than alpha particles?
They have a significantly smaller mass
What are 4 applications of radiation?
- Measuring the thickness of materials
- Tracers
- Radiotherapy
- Sterilisation
Which particles are used to measure the thickness of materials?
Beta
What is radioactive decay?
Spontaneous disintegration of an unstable nucleus into a more stable one
What happens during α- or β-decay?
The nucleus changes to that of a different element
What is meant by the half-life of a radioactive isotope?
Time taken for the activity of any given sample to fall to half its original value
What are the effects of ionising radiations on living
things?
- Causes mutations
- Causes cancer
- Kills the cell
Describe how radioactive materials can be handled in a safe way
Pick up with a pair of tongs
Describe how radioactive materials can be used in a safe way
It is left out of its container for as short a time as possible
Describe how radioactive materials can be stored in a safe way
Store in a lead container
