About ionic bonds (and ionic compounds) [closed]








**Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers.
 
 






---








**Want to improve this question?** Update the question so it focuses on one problem only by [editing this post](/posts/57003/edit).




Closed 7 years ago.








[Improve this question](/posts/57003/edit) 



I have a few questions:


1. **All** ionic bond occurs between a metal and a non-metal. Is this true? In the definition of *metal* and/or *non-metal* are the metaloids included? In the definition of *non-metal* are all diatomic and polyatomic non-metals included? Meaning all of those elements form ionic bonds with metals?
2. When 2 charged molecules form an ionic bond, how is the compound classified?
3. For ionic compounds formed by only 2 different elements, knowing the metal and the non-metal in question, is it possible to have more than one formula for the compound? I think this is probably possible and maybe even common for the transition metals, because we usually see those roman numerals in their formulae. Am I correct in assume transition metals can form different ionic compounds (meaning different formula) with one same element? If yes, why does that happen?
4. does item 3 extends to charged molecules?




1. Not exactly. In ammonium chloride ($\ce{NH4Cl}$), the bond is between a cation ($\ce{NH4^+}$) that has a non metal as its central atom. So the condition that ionic compounds are formed between metal cations and non metal anions is not necessary. Additionally, you will find many organic compounds where the anions or the cations are made up of many atoms, that is the cation itself consists of many atoms, and likewise for the anions. (I guess this was what you meant by charged molecules!). Organic cations (where the cation is not a metal cation) usually have their positive charge centered on a nitrogen atom. Secondly, almost all the non metals are capable of forming ionic bonds, regardless of whether they are diatomic or polyatomic in their elemental state.
2. It is called an ionic compound.
3. Yes, in fact transition metal compounds can have different formulae with the same metal and non metal elements! The best example would be $\ce{FeO}$ and $\ce{Fe2O3}$. So why do these different formulae exist? Here is a hint: $\ce{FeO \;=\; Fe^{+2} + O^{-2}}$ and $\ce{Fe2O3\;=\; 2Fe^{+3} + 3O^{-2}}$. Did you spot it? In the first compound, there are $\ce{Fe^{+2}}$ cations, while in the second one, there are $\ce{Fe^{+3}}$ cations! Why does this happen? Well some metal atoms can show two or even more different valencies. For example, once iron has lost the first two electrons, it has the possibility to lose the third electron as well, so it can show both types of positive charge on it, +2 as well as +3. Same is with other cations.
4. Not sure if anything like that happens. The problem is that generally only metals can lose an extra electron without changing the cation structure, charged molecules may require to change their structure to change the amount of charge they hold. The closest I know is [transition metal complexes](https://en.wikipedia.org/wiki/Coordination_complex). The cation *does* change its compostion in various compounds (as a whole cation), but the central metal atom can remain the same. That is pretty advanced stuff though. You will learn about it in higher classes (in class 12).


 1