How can you tell if a compound is Iconic Or Covalent when there are multiple elements in the formula?

Question

I know the difference between ionic and covalent when there are two elements, but not when there are more than two.

Answer 1

A caveat before any explanation is that most compounds (other than those that are completely non polar) are neither 100% ionic nor 100% covalent. Even NaF is only about 88% ionic, whereas H₂ is 0%

ionic. Having stated that, the answer to your question will depend on the nature of the compound in question. For example, Na₃PO₄ has 3 different types of elements. It is mostly ionic because it dissociates into 3Na⁺ and a PO₄^3- ion. It can be viewed as a product of an acid (H₃PO₄) and a base (NaOH) producing a salt. In these instances, the compound will be mostly ionic. If you consider something like urea (NH₂CONH₂) having 4 different types of atoms, it is considered covalent as it does not form ions when in solution. Not sure this totally answers your question, but if you submit specific examples, it may be easier to explain their category.