Writing Formulas from names
Posted: Wed Nov 11, 2015 2:44 pm
Number 17.31a asks for the formula of potassium hexacyanidochromate(III). From my understanding, the roman numerals at the end of the name implied that the chromate ion had an oxidation state of 3+. This would mean that the [Cr(CN)6] part of the compound would have a net positive charge, and if it were to bond with potassium, the potassium would have to have a negative charge. I know that potassium is almost always a cation; however, I thought chromium was the same way, and one of them has to be negative. Are we just supposed to assume that the roman numerals are indicative of a negative charge on the Cr ion because potassium has such a low ionization energy? Is it common for transition metals to have negative charges in coordination compounds?