a) i) Explain what is meant by the term 'isotopes', giving TWO examples with their nuclide symbols. ii) Carbon has two stable isotopes: carbon-12 (abundance 98.89%) and carbon-13 (abundance 1.11%). Calculate the relative atomic mass of carbon, giving your answer correct to two decimal places. b) i) State Hund's rule of maximum multiplicity. ii) Draw the orbital diagrams (box notation) showing the arrangement of electrons in the following subshells for nitrogen (Z = 7) and oxygen (Z = 8), and use your diagrams to explain why nitrogen is more stable than oxygen. c) i) Define the term 'electron affinity'. ii) The electron affinities of the halogens are: F = -328 kJ/mol, Cl = -349 kJ/mol, Br = -325 kJ/mol, I = -295 kJ/mol. Explain why chlorine has a more negative electron affinity than fluorine, even though fluorine is more electronegative. d) State TWO differences between the properties of metals and non-metals as observed in the periodic table, relating each difference to their positions in the table.