Atomic structure

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Sample objectives

What this unit covers

• Atoms and isotopes: Define atomic number as the number of protons in the nucleus of an atom.
• Atoms and isotopes: Compare the composition of two isotopes of the same element.
• Atoms and isotopes: Explain that atoms can form ions by losing or gaining electrons.
• Atoms and isotopes: Describe the nucleus as the small central part of an atom.
• Atoms and isotopes: Describe how the discovery of the electron led to the plum pudding model.
• Atoms and isotopes: Describe how Bohr adapted the nuclear model by suggesting that electrons orbit at specific distances or energy levels.
• Atoms and nuclear radiation: Distinguish contamination from irradiation.
• Atoms and nuclear radiation: Describe how ionising radiation can damage cells and DNA.
• Atoms and nuclear radiation: Explain that alpha decay decreases mass number by 4 and atomic number by 2.
• Atoms and nuclear radiation: Represent gamma emission using a nuclear equation or written description.
• Atoms and nuclear radiation: Define half-life as the time taken for the number of radioactive nuclei in a sample to halve.
• Atoms and nuclear radiation: Explain why it is impossible to predict when an individual unstable nucleus will decay.
• Atoms and nuclear radiation: Describe alpha radiation as a helium nucleus containing two protons and two neutrons.
• Atoms and nuclear radiation: Define radioactive decay as the process in which an unstable nucleus emits radiation.
• Hazards and uses of radioactive emissions and of background radiation: Interpret charts or tables showing sources of background radiation.
• Hazards and uses of radioactive emissions and of background radiation: Identify natural sources of background radiation, including rocks, cosmic rays, radon gas, food and living organisms.
• Hazards and uses of radioactive emissions and of background radiation: Explain why isotope choice depends on balancing usefulness and exposure risk.
• Hazards and uses of radioactive emissions and of background radiation: Explain why a very short half-life may make a source difficult to use.
• Hazards and uses of radioactive emissions and of background radiation: Explain why gamma emitters are often used as medical tracers.
• Hazards and uses of radioactive emissions and of background radiation: Describe how beta or gamma radiation can be used to monitor the thickness of materials.
• Nuclear fission and fusion: (Physics only) Describe fusion of hydrogen nuclei as a process that can form helium.
• Nuclear fission and fusion: (Physics only) Explain why fusion requires very high temperatures.
• Nuclear fission and fusion: (Physics only) Describe how a neutron is absorbed by a large nucleus before fission.
• Nuclear fission and fusion: (Physics only) Distinguish a controlled chain reaction in a nuclear reactor from an uncontrolled chain reaction.