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P4
| Question | Answer |
|---|---|
| How can electrons change energy level | Absorbing or emitting radiation |
| What is the atomic number | Number of protons |
| What is the mass number | No of protons + no of neutrons |
| What is an isotope | An element with a different number of neutrons |
| Describe the development of the atom | -First atoms were thought to be solid spheres which couldn't be divided -plum pudding model -alpha particle scattering experiment proved that there was a positive nucleus with electrons orbiting is shells James Chadwick proved the existence of neutrons |
| Describe the alpha particle scattering experiment | -alpha particles fired at gold foil -most went straight through -some deflected at angles -only a few bounced off |
| Define activity | The rate at which a source of unstable nuclei decays |
| Define count rate | Number of radioactive counts per second |
| What are the 4 types of nuclear decay | -alpha -beta -gamma -neutron |
| Describe alpha radiation | -helium nucleus -stopped by a peice of paper -strongly ionising |
| Describe beta radiation | -high speed electron -moderatly ionising -absorbed by aluminium |
| Describe gamma radiation | -electromagnetic wave -weakly ionising -absorbed by thick lead |
| Define half-life | The time it takes for the number of radioactive nuclei in a sample to half |
| Define contamination | The presence of radioactive atoms on other materials |
| Define irradiation | Exposure of an object to radiation |
| Give 2 examples of natural sources of background radiation | -cosmic rays -rocks |
| Give 2 examples of man made sources of background radiation | -nuclear accidents -fallout of nuclear weapons testing |
| What affects a person's level of radiation | -job -location |
| What is radiotherapy | High ionising radiation directed at cancer cells to kill them |
| What are the risks of using radiation | -tissue damage -cancers -radiation sickness |
| Describe the process of nuclear fission | -radiation nucleus hit by neutron -neutralises absorbed -nucleus splits into two lighter nuclei -neutralises and energy released -neutralises can cause a chain reaction |
| Describe the process of nuclear fusion | Two light nuclei collide and fuse to form larger nucleus this releases energy |
Created by:
Liam P
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