Topic 6 – Radioactivity

6.1 Describe an atom as a positively charged nucleus, consisting of protons and neutrons, surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus 

5b 

6.2 Recall the typical size (order of magnitude) of atoms and small molecules 

 6.3 Describe the structure of nuclei of isotopes using the terms atomic (proton) number and mass (nucleon) number and using symbols in the format using symbols in the format 

 6 13C 

6.4 Recall that the nucleus of each element has a characteristic positive charge, but that isotopes of an element differ in mass by having different numbers of neutrons 

6.5 Recall the relative masses and relative electric charges of protons, neutrons, electrons and positrons 

 6.6 Recall that in an atom the number of protons equals the number of electrons and is therefore neutral 

 6.7 Recall that in each atom its electrons orbit the nucleus at different set distances from the nucleus 

6.8 Explain that electrons change orbit when there is absorption or emission of electromagnetic radiation 

6.9 Explain how atoms may form positive ions by losing outer electrons 

6.10 Recall that alpha, β– (beta minus), β+ (positron), gamma rays and neutron radiation are emitted from unstable nuclei in a random process 

 6.11 Recall that alpha, β– (beta minus), β+ (positron) and gamma…