P7 - Radioactivity Flashcards
(28 cards)
How can the electron arrangements of the nucleus change?
- The absorption of electromagnetic radiation causes electrons to move further from the nucleus
- The emission of electromagnetic radiation causes electrons to move closer
Why do atoms have no overall electrical charge?
The number of electrons is equal to the number of protons
How do atoms form positive ions?
They lose one or more electrons
What are isotopes?
Atoms of the same element with different numbers of neutrons
What is radioactive decay?
The random process where the nucleus gives out radiation to become stable
What is activity?
The rate at which a source of unstable nuclei decay
What is the unit for activity?
Becquerel, Bq
What is count rate?
The number of decays recorded each second by a detector
What is count rate?
The number of decays recorded each second by a detector
What is an alpha particle?
- Two neutrons and two protons
- Helium nucleus
What is a beta particle?
- High speed electron
- Ejected from the nucleus as a neutron turns into a proton
What is a gamma ray?
Electromagnetic radiation from the nucleus
Alpha radiation
- Least penetrating + unable to pass through a sheet of paper
- Least range in air - 5cm
- Most ionising
- Short range is very dangerous because of how ionising it is
- Long range isn’t dangerous because it has a short range
Beta radiation
- Penetrate more than alpha, less than gamma
- Can travel a few metres
- Moderate ionisation power
- Short range is very dangerous because of how ionising it is
- Long range is not dangerous because it can only travel a few metres
Gamma radiation
- Most penetrating, through most materials like human tissue
- Unlimited range in air
- Least ionising
- Short range is very dangerous because it can penetrate deeply
- Long range is dangerous because they have unlimited range
What happens during beta decay?
A neutron decays into a proton and an electron
What is contamination?
The unwanted presence of materials containing radioactive atoms on other materials
What is irradiation?
The process of exposing an object to nuclear radiation. The irradiated object does not become radioactive
What are the hazards of irradiation?
Irradiation can cause acute effects like skin burns at high doses and increase the risk of long-term effects like cancer
Where does background radiation come from?
Rocks, cosmic rays from space, fallout from nuclear weapons testing and nuclear accidents
What may the level of background radiation and radiation dose be affected by?
Occupation and location
What is radiation dose measured in?
Sieverts(Sv)
Why do the hazards associated with radioactive material change according to the half-life?
Substances with shorter half-lives decay more rapidly and have higher radiation levels, posing a greater hazard
What uses do we have for nuclear radiation?
Exploration of internal organs, control or destruction of unwanted tissue
