Differentiate an ionic from a covalent compounds

In summary: Aluminum fluoride is more ionic than silicon fluoride because the aluminum atoms coordinate to more fluorines. But even in SiF4, the silicon atom only coordinates to its own four fluorines.
  • #1
Godwin Kessy
91
0
I have come to a situation that I can hardly differentiate an ionic from a covalent compounds!
Before this confusion I had firstly known that whenever I find a compound with constituents of atoms with a very large difference in electronegativity, then i just conclude that its ionic, or when I find it in form of crystal, If it can dissolve in water the =n it is an ionic bond

But During my thoroughly studying of bonding I found most of metals forming covalent bond and just from there I couldn't straight way tell, unless I know the compound very well and have seen it probably!

Take an example of AlF6, Fe2O3
Are these ionic or covalent compounds?
 
Chemistry news on Phys.org
  • #2


Welcome to the chemistry :wink:

Not every compound can be easily classified. In the case of every bond there is some "ionicity" and some "covalenticity" - if one character prevails, we can classify the bound as either covalent or ionic, but sometimes it is not possible.
 
Last edited by a moderator:
  • #3


can the F and Al dissociate in water? same with Fe and O. If they can then it's ionic.
 
  • #4


mazinse said:
If they can then it's ionic.

Following this logic gaseous HCl is ionic as well. Rest assured it is not.
 
Last edited by a moderator:
  • #6


No idea what you are referring to. There is one general chemistry that is base of both chemistry and biochemistry. Sometimes definitions used in different areas of science differ, but reality is always one - HCl doesn't behave differently in chemistry or biochemistry labs.
 
Last edited by a moderator:
  • #7


There's no black-and-white of covalent/ionic, unless you're practicing 19th century chemistry.

It's a sliding scale. Basically the amount of 'ionic' versus 'covalent' character can be quantified by the difference in the respective electronegativities of the atoms involved. For the definitive explanation of the concept, see Chapter 3 of Pauling's "The Nature of the Chemical Bond".

He brings up AlF3 (which I think you mean?) Quoting the man:
Linus Pauling said:
[O]f the fluorides of the second-row elements:
Melting point: NaF 995C MgF2 1263 AlF3 1257 SiF4 -90 PF5 -94 SF6 -51
those of the high melting points have been described as salts, and the others as covalent compounds; and the great change from aluminum to silicon fluoride has been interpreted as showing the bonds change sharply from the extreme ionic type to the extreme covalent type. I consider the bonds in aluminum fluoride to be only slightly different in character from those in silicon flouride, and I attribute the abrupt change in properties to the change of the atomic arrangement.

(He then explains that the first three are octahedral; each metal atom coordinates to a number of fluorines from another metal atom. But in SiF4, each silicon atom coordinates only to its own four fluorines, and the whole thing is held together by weak van der Waals forces between the SiF4 molecules.)


It's good to be able to tell if a bond is more ionic or covalent in character, but a strict distinction between covalent and ionic isn't possible, and therefore not very useful.
 

Related to Differentiate an ionic from a covalent compounds

1. What is the main difference between ionic and covalent compounds?

The main difference between ionic and covalent compounds is the type of chemical bond that holds them together. Ionic compounds are held together by electrostatic attraction between positively and negatively charged ions, while covalent compounds are held together by the sharing of electrons between atoms.

2. How can you determine if a compound is ionic or covalent?

A compound can be determined as ionic or covalent based on the types of elements present. Ionic compounds are typically made up of a metal and a nonmetal, while covalent compounds are made up of two or more nonmetals.

3. What are some properties of ionic and covalent compounds?

Ionic compounds tend to have higher melting and boiling points, are usually soluble in water, and conduct electricity when dissolved in water. Covalent compounds, on the other hand, tend to have lower melting and boiling points, are mostly insoluble in water, and do not conduct electricity.

4. Can a compound have both ionic and covalent bonds?

Yes, some compounds can have both ionic and covalent bonds. These are called polar covalent compounds and have a partial separation of charges within the molecule due to differences in electronegativity between the atoms.

5. How do you name ionic and covalent compounds?

Ionic compounds are named by writing the name of the metal first, followed by the nonmetal with the suffix -ide. Covalent compounds are named using prefixes to indicate the number of atoms present for each element and the suffix -ide for the last element in the compound.

Similar threads

  • Chemistry
Replies
7
Views
8K
Replies
6
Views
14K
  • Biology and Chemistry Homework Help
Replies
1
Views
907
  • Chemistry
Replies
3
Views
2K
Replies
1
Views
2K
  • Chemistry
Replies
1
Views
2K
Replies
15
Views
5K
  • Biology and Chemistry Homework Help
Replies
3
Views
4K
Back
Top