Why can arranging elements strictly by relative atomic mass put a pair in the wrong order?
Relative atomic mass depends on isotope abundances
Atoms with more protons always have a greater mass
Relative atomic mass changes when an element forms ions
Relative atomic mass does not include the mass of neutrons
80 exam-style questions on Edexcel GCSE Chemistry 2.2 The periodic table, covering 2.2.1 Mendeleev's periodic table, 2.2.2 Periods, groups, metals and non-metals, and 2.2.3 Electronic configuration and position in the periodic table. Each one has a worked solution and a mark scheme showing where the marks go.