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Which type of bond is stronger than the other - ionic or covalent?

Hello,

My book says that ionic bond is the strongest bond, but I really don't get it. If I compare an ionic compound like Aluminium Oxide(with large charges, hence large electrostatic forces) with a covalent compound like Diamond, there's a VERY large difference between their boiling points(as bps give the best indication of type of forces).

Diamond's Boiling point: 4827^oC
Aluminium Oxide's Boiling point: 2977^oC

Is the book wrong? :confused:

Reply 1

Rtcw

Usually ionic is stronger. However, in this case, covalent is stronger because of how carbon atoms are structured, not because of the bond.

Reply 2

Steellio14

One isn't stronger than the other I don't think - it depends on the element/s involved in the bond. Diamond is in the form of a covalent network which explains why it is stronger than aluminium oxide :smile:

Reply 3

illusionz

It's difficult to compare them fairly, because of the nature of compounds with the different sorts of bonds. Also, not many elements which form ionic bonds will also form covalent bonds. You'd have trouble studying the covalent bonding of metals, for example.

The issue is that lots of bonding is not 100% ionic or 100% covalent - you have polar covalent bonds, and covalent bonding has a lot more variables to do with geometry and orbital overlap which is not present in the electrostatic attractions in ionic compounds.

(edited 12 years ago)

Reply 4

EierVonSatan

As illusionz says, it's hard to compare them. You can compare the strengths of a single covalent bond and say that H-H us stronger than Cl-Cl but comparing H-H with (say) NaCl is harder since you can't isolate a single ionic bond - you have to look at the lattice enthalpy. Broadly speaking, ionic compounds have higher melting and boiling points than covalent compounds - but as with everything is chemistry, there are always exceptions (and these are often the interesting ones!) :smile:

(edited 12 years ago)

Reply 5

illusionz

Broadly speaking, ionic compounds have higher melting and boiling points of covalent compounds - but as with everything is chemistry, there are always exceptions (and these are often the interesting ones!) :smile:

Just in case anyone read this to imply that ionic bonding is stronger than covalent bonding, it doesn't!!!

The melting point of a covalent compound is related to the inter-molecular bond strength (eg hydrogen bonds, dipole-dipole interactions etc), NOT covalent bond strength.

Reply 6

Daniel-

covalent is the strongest obsiuosly
what the strongest substance in the wolrd??
a diamond
which is a covalent bond :P

Reply 7

illusionz

Original post by Daniel-

covalent is the strongest obsiuosly
what the strongest substance in the wolrd??
a diamond
which is a covalent bond :P

Did you not read the thread?

Reply 8

SalBhatti

Thanks everyone. :smile:

Reply 9

ayanthi927

Melting point has nothing to do with the bond being strong or weak. Melting means the intermolecular distance increases. It doesn't imply that the bond breaks.