which of the compounds are ionic compounds?
<answer> The compound is an ionic compound which contains either or perhaps both ions in the form of a polyatomic ion held together by covalent bonds. <context> There is a class of compounds, many of them very familiar, which contain more than two elements and also both ionic and covalent bonding. The compound is an ionic compound which contains either or perhaps both ions in the form of a polyatomic ion held together by covalent bonds. Most polyatomic ions are negatively charged; only the hydronium ion and the ammonium ion are positively charged.