P8 - Atomic Physics Flashcards
Describe the structure of the nucleus of an atom [2]
The nucleus is positivity charged and is made of protons (positive) and neutrons (neutral)
What are the relative charges of protons, neutrons and electrons? [3]
Protons +1 / Neutrons 0 / Electrons -1
What are the relative masses of protons, neutrons and electrons? [3]
Protons 1 / Neutrons 1 / Electrons 0.0005
What is an isotope? [3]
Atoms of the same element / with the same number of protons / but with a different number of neutrons
What is the same about all atoms of the same element? [1]
The have the same number of protons (atomic number)
Describe α radiation [3]
An α particle consists of 2 protons and 2 neutrons (same as a Helium nucleus) / highly ionising / weakly penetrating (blocked by 5cm of air)
Describe β radiation [3]
A β particle is an electron from the nucleus of an atom / medium ionising / medium penetration (blocked by 50cm of air or a sheet of metal)
Describe γ radiation [3]
Electromagnetic radiation / weakly ionising / highly penetrating (blocked by several cm of lead)
How is α radiation affected by electric and magnetic fields? [2]
Slightly deflected / because an α particle has a positive charge
How is β radiation affected by electric and magnetic fields? [3]
Greatly deflected / in the opposite direction to α radiation because it is negatively charged / deflected more than α radiation because it is much lighter
How is γ radiation affected by electric and magnetic fields? [2]
It is not deflected / it has not charge
What is background radiation? [1]
Weak radiation from external sources which is always present
Give four sources of background radiation [4]
Cosmic rays / rocks underground / nuclear fallout / medical rays
How can radiation be detected? [3]
Photographic film / Geiger-Muller tubes / cloud chamber
Define half life [2]
The time taken for the number of radioactive nuclei to halve / or the time taken for the count rate (activity) to halve
Give three practical applications of radioactive materials [3]
Medical tracers / radiotherapy / smoke alarms / sterilisation of equipment / checking thickness of a material in manufacturing
What are the risks of ionising radiation to people? [3]
It can damage living cells / cause the cells to die or mutate / can lead to cancer
Explain why some material is radioactive and why it decays [4]
Nuclei with too many or too few neutrons (called isotopes) / are unstable / decay by emitting radiation / this is a random process
What are some safety precautions when using radiation? [3]
Minimise exposure time / keep as much distance from the source / use shielding (e.g. Lead)
