Topic 4- Atomic Structure Flashcards
State 4 types of nuclear radiation
- Alpha particles
- Beta particles
- Gamma rays
- Neutrons
What are the constituents of an alpha particle?
Two protons and two neutrons
The same as a helium nucleus
What will stop beta radiation from passing through a point?
Thin sheet of aluminium
Several meters of air
What will stop gamma radiation passing through a point?
Several cm of lead
A few cm of concrete
Which type of radiation is most ionising?
Alpha
Which type of radiation is least ionising?
Gamma
What changes to mass and charge occur due to gamma ray emission?
Both stay the same
What is the nature of radioactive decay?
Random- nuclei radiation is completely by chance
Impossible to predict
Define the half life of a radioactive isotope
Time it takes for unstable nuclei in substance to halve
What is radioactive contamination?
Presence of unwanted radioactive nuclei on other materials
What is irradiation?
Process of exposing material to nuclear radiation
Material doesn’t become radioactive
Which 2 ways can an atoms electron arrangement be changed?
- Absorbing electromagnetic radiation
2. Emitting electromagnetic radiation
How does an atoms electron arrangement change when it absorbs electromagnetic radiation?
Electrons move away from nucleus
Move to a higher energy level
How does an atoms electron arrangement change when it emits electromagnetic radiation?
Electrons move close to nucleus
Move to lower energy level
Give 4 sources of background radiation
- Rocks
- Cosmic rays from space
- Nuclear weapon testing
- Nuclear accidents
What is the unit used to measure radiation dosage?
Sieverts
Why might the radiation dosage different people experience differ?
Background radiation differs in different locations due to locality of nuclear power stations
What factor determines how dangerous a particular radioactive isotope is?
The half- life of the isotope
Why are isotopes with long half lives harmful?
- remain radioactive for long periods of time
- must be stored to prevent humans and the environment being exposed to radiation for too long
State 2 uses of nuclear radiation in the field of medicine?
- Examining internal organs
2. Controlling + destroying unwanted tissue
How is radiation used in sterilisation?
Gamma emitters kill bacteria on equipment
What is the process of radiotherapy?
- Gamma emitters direct gamma rays at cancerous cells
2. Cancerous cells absorb radiation and are killed
What is nuclear fission?
Splitting of large unstable nuclei from small stable nuclei
What needs to happen to induce fission?
Unstable nuclei must absorb neutrons
Alongside small nuclei, what else is emitted during fission?
Gamma rays
2/3 neutrons
Neutrons
What form of energy do all fission products have?
Kinetic energy
What takes place in a chain reaction?
- unstable nucleus absorbs neutron
- nucleus undergoes fission and emits 2/3 neutrons
- these induce more fission : chain reaction
What is the consequence of an uncontrolled chain reaction?
Rate of events too high; too much energy production
Can lead to nuclear explosion
