Apologia Chemistry: Ionic Compounds and Common Misunderstandings

 My Chemistry class is finishing timelines and have begun ionic compound nomenclature or naming.  Wow.  We uncovered a bunch of common misunderstandings.  Let’s start with Po, polonium, an element, and PO4 -3, phosphate, a polyatomic ion. They confuse PO4 -3 and P-3, which is phosphide.   Here’s another common mistake: sulfate or SO4-2, sulfite or SO3-2, and S-2 or sulfide.  I went over the Stock System.  Some elements, such as Fe +2, Fe+3, Cu +1, and Cu+2 have a variable oxidation state.  Sometimes copper release one electron, other times it releases two electrons.  Cu +1 is copper I.  Cu +2 is copper II.  Kids then proceed to add Roman numerals to ALL ions, such as Na +1.  One more common mistake kids make is to write phosphate as PO -3 instead of PO4 -3.  See structure.  Phosphate is group of bonded atoms which act as an anion or negative ion.  Correct the mistakes and use them for instruction.  One more tip.  Sulfate is also correctly spelled sulphate in Canada, England, and Australia.  Point out the difference in spelling.