Abstract
The article concerns five traditionally difficult issues that chemical educators encounter and how they should be resolved. In some cases I propose the examination of necessary and sufficient conditions in order to cast light on the relationships under discussion. The five educational issues are, the notion that a pH value of seven implies a neutral solution of water and vice versa, the use of Le Châtelier’s Principle, the relative occupation and ionization of 4s and 3d orbitals, the explanation of anomalous electronic configurations and the elements that make up group 3 of the periodic table.