FeO Li2O CO2 N2O4 SrO XeO3 K2O...ionic or molecular?

Answer 1

To form an ionic compound you need to form both a positively charged ion (cation) and a negatively charged ion (anion). Metals are the most likely candidates for forming cations because they typically have low ionization energies, so it won't be too difficult (i.e. won't cost that much energy) to remove electrons from them. Of all the elements, the ones that are most likely to form anions are the non-metals (excluding the noble gases), because they typically have large electron affinities, meaning they give off a lot of energy when you add an electron (or electrons) to them. So to find out which compounds are ionic, look for compounds made up of a metal and a non-metal. Those would be: FeO, Li2O, SrO, and K2O Covalent compounds are typically formed whenever you have two elements who are so similar in their ability to attract electrons that neither is dominant enough to take the electron from the other (kinda). Covalent bonds can form both from two (or more) non-metals or from two (or more) metals. Covalent metal bonds are usually classified as a special kind of covalent bond called a metallic bond. So the elements that are covalent (all non-metal/non-metal examples) are: CO2, N2O4, and XeO3.