Periodicity — solubility and acid/base behaviour of Na–S oxides in water
“Descriptions of the reactions of the oxides with water did not appear to be well known… candidates were required to know that aluminium oxide and silicon(IV) oxide are insoluble, that magnesium oxide and sodium oxide react with water to produce alkaline solutions and that magnesium hydroxide is only slightly soluble.”
Pick an oxide and add it to water. The pH meter and solubility label show the trend across Period 3 — alkaline on the left, insoluble in the middle, acidic on the right.
Sweep left to right: the metallic ionic oxides give alkalis, the middle amphoteric/giant-covalent oxides are insoluble, and the non-metal molecular oxide gives a strong acid.
Original reconstruction inspired by the misconceptions described in the Singapore-Cambridge GCE A-Level H1 Chemistry 8873 November 2023 Examiner Report. Not the actual examination question. For classroom exploration.
Made by lookang, using Claude Fable 5. More resources: iwant2study.org