P4: Atomic Structure Flashcards
Explain how the properties of alpha, beta, gamma radiation affects the level of the hazard at different distances (4)
- At short distances, the most hazardous radiation would be alpha radiation
- as it has the highest ionizing power
- at long distances gamma radiation would be the most hazardous
- as it has the highest penetrating power
- medium distance: beta is more hazardous than gamma as it has a higher ionizing power but less hazardous than alpha
Give 4 sources of background radiation (natural + man-made
natural:
- rocks
- cosmic rays from space
man-made:
- nuclear power / weapons
- medical imaging
Define background radiation
- low-level radiation that is around us all the time
What is the unit used to measure radiation dosage?
- sieverts (Sv)
What factor determines how dangerous a particular radioactive isotope is?
- the half life of the isotype
What factor determines how dangerous a particular radioactive isotope is?
- the half-life of the isotype
Why are isotypes with long half-lives particularly harmful?
- they remain radioactive for much longer particularly periods of time
State two uses of nuclear radiation in the field of medicine
- Examining of internal organs
- Controlling and destroying unwanted tissue
State a use for each type of radiation
alpha: smoke detectors
beta: used in medical tracers to explore internal organs
gamma: treat cancer cells or sterilisation
Explain the process of radiotherapy using gamma radiation
- gamma emitters direct gamma rays at the cancerous cells
- the cancerous cells absorb the radiation and are killed
Describe how radioactive tracers’ work (4)
- patients drink a small amount of radioactive isotype that emits ionizing radiation (beta or gamma)
- the tracer passes through the organ
- if the organ is healthy, the tracer will flow through it in the blood
- if the organ is blocked, the tracer will be stopped, and radiation will be detected for longer
give 4 properties a medical tracer must have to be chosen
- must emit radiation that can be detected (high penetrating power) from outside the body
- must not be strongly ionizing to minimize damage to the body tissue
- must have a short half life
- must not decay into another radioactive isotype
Describe how nuclear radiation is used to destroy a tumor using a radioactive implant. Include details about half life (4)
- small implant of radioactive isotype placed in tumor
- radiation from isotype destroys cancer cells
- use isotype with short half-lives to ensure healthy cells are not damaged
- do not make half times too short otherwise the radiation would not have time to kill cancer cells
Explain why the source chosen for a tracer should have a short half life (2)
- as short half-life means the level or radiation
- decreases rapidly
How can workers reduce their exposure to radiation (2)
- protective clothing such as lead lines coats
- reduce exposure times
Describe the process of nuclear fusion (4)
- an unstable nucleus
- must absorb a neutron
- the nucleus splits into two smaller nuclei
- and releases 2 or 3 neutrons and energy
What is a chain reaction in terms of nuclear fission?
- when the neutrons released in a fission reaction cause further fission reations
Describe a chain reaction in terms of nuclear fission
- each released neutron from nuclear fission, if travelling at the right slow speed, can be absorbed by another nucleus causing further fission reactions
What is the consequence of an uncontrolled chain reaction
- the rate of fission events becomes to high and results in the production of too much energy
- this can led to a nuclear explosion
What are the three main components of the core a nuclear reactor?
- fuel rods
- control rods
- moderator
What is the role of the moderator in a nuclear reactor?
- to slow down the neutrons so they are travelling at speeds which allow them to be absorbed by fissile nuclei and cause fission
Why is the reactor in a thick steel vessel, surrounded by concrete ( 2 )
- to withstand the high temperature and pressure in the nuclear reactor core
- steel absorbs any ionising radiation that escapes
Explain what happens in the process of nuclear fusion (3)
- light nuclei
- join to form a heavier nucleus
- mass of the nuclei is converted to energy
give the approximation for the radius of an atom
1 x 10 “ -10 metres
What are the three subatomic constituents of an atom
- proton
- neutron
- electron
where is the mass of an atom mostly concentrated
in the nucleus
Approximately what proportion of the total radius of an atom is the radius of the nucleus
1/ 10,000 metres
Describe the arrangement of protons , neutrons and electrons in an atom
- the protons and neutrons are found in the atom’s nucleus
- the electrons are found in discrete energy levels around the nucleus
what type of charge does the nucleus of an atom have? Why?
- positive charge
- the nucleus contains protons and neutrons
- protons have a positive charge
- neutrons have no charge
Give two ways that an atom’s electron arrangement can be changed
- Absorbing electromagnetic radiation
- Emitting electromagnetic radiation
Explain how an atom’s electron arrangement changes when it absorbs EM radiation.
- electrons move further from the nucleus
- to a higher energy level.
Explain how an atom’s electron arrangement changes when it emits EM radiation.
- electrons move closer to the nucleus
- to a lower energy level.