Which melting point would indicate a metallic structure? [closed]








**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
 
 






---








**Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/91842/edit).




Closed 5 years ago.








[Improve this question](/posts/91842/edit) 




> 
> **Question**  
> 
>  If you have three substances with three different melting points;
> 
> 
> 1. 445 °C
> 2. 1907 °C
> 3. -7 °C
> 
> 
> Which of these would most likely have a metallic structure?
> 
> 
> 


I understand that the third option would most likely be covalent. But between the first and second option, there are many bonds which have a similar melting point to both answers. Which of these would most likely indicate a metallic strucure to be involved.




Now, before we get to the "expected theoretical" answer, I should make one point clear: **predicting** the solid state **just** based on the melting point data **can not be perfect**! Browsing the data on [melting points on Wikipedia](https://en.wikipedia.org/wiki/Melting_points_of_the_elements_(data_page)), you'll find that vanadium has a melting point of $\pu{1910 ^\circ C}$, while zinc has a melting point of $\pu{420^\circ C}$. Both these values are very close to the options (1) and (2), hence, one can very well argue that **both** the options represent a **metallic structure**. 


But this is definitely not the answer your teacher expects. A theoretical (and again, practically wrong) approach instead is to realize that the values of intermolecular forces increase in the order of molecular solid < metallic solid < ionic solid < covalent networked solid. Thus, the option (3) is probably a molecular solid, option (1) can be either an ionic solid or a covalent networked solid, while option (2) must be the metallic solid as expected.




---



> 
> I understand that the third option would most likely be covalent.
> 
> 
> 


Just get rid that misconception already. Covalently bonded networked solids have higher melting points than several metals and even ionic solids! Diamond melts at $\ce{3800 K}$, while boron melts at $\ce{2349K}$. Our beloved ionic solid sodium chloride melts at a poor $\ce{1073K}$, while all the 3d series metals melt under $\ce{2200K}$! Hence, the assumption, that low melting point indicates a covalent solid, is false.


 4