The chemical properties of the volatile elements in groups 15 to 18 are outlined, showing how the the periodicicty of the properties of the elements shapes their chemistry. The manufacture of hydrogen and chlorine is described, showing how mercury-free methods have been developed for the latter. The effect of the formation of atmospheric CO2 on atmospheric oxygen content is explained in terms of dissolution in the oceans. Remediation of the exhaust gases from internal combustion engines by catalysts to remove CO2, NOx and carbonaceous particulates is explained. Options for carbon capture and storage by physical and chemical processes are evaluated, and examples provided of these processes in operation. Exploitation of the atmosphere for energy capture using wind turbines has been aided by the development of high performance magnets. The basis of these magnets and the role of rare earth elements is explained.
