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Specialty Chemistry Forums => Citizen Chemist => Topic started by: Zeus on September 04, 2015, 01:51:18 PM

Title: Atomic bonding
Post by: Zeus on September 04, 2015, 01:51:18 PM
If an ionic bond is stronger than a covalent bond, would the physical solid state compound of an ionic bond be more difficult to puncture/ destroy than a covalent bond?
Title: Re: Atomic bonding
Post by: Arkcon on September 04, 2015, 02:29:29 PM
If an ionic bond is stronger than a covalent bond,

Generally considered so, but only in the most general terms.

Quote
would the physical solid state compound of an ionic bond be more difficult to puncture/ destroy than a covalent bond?

OK, you're mixing metaphors a little bit here.  I guess you mean to ask, are solids, made up of ionic bonds, stronger than those made of covalent bonds.  You can search these types of compounds yourself, you may find confirmation, and maybe a few exceptions.
Title: Re: Atomic bonding
Post by: Zeus on September 04, 2015, 03:53:14 PM
Quote

OK, you're mixing metaphors a little bit here.  I guess you mean to ask, are solids, made up of ionic bonds, stronger than those made of covalent bonds.  You can search these types of compounds yourself, you may find confirmation, and maybe a few exceptions.

That post did get a little confusing there, didn't it? Haha.
Sorry, chemistry isn't my first language.
I'm looking to produce a mixture with some specific physical qualities in order to sell as a consumer product.
Title: Re: Atomic bonding
Post by: Arkcon on September 04, 2015, 06:04:16 PM
Specifically?
Title: Re: Atomic bonding
Post by: Enthalpy on September 06, 2015, 06:04:29 PM
The mechanical resistance of a compound isn't trivial to define and relates very little with the strength of the chemical bonds between the atoms.

First, if you try to deduce a break stress from the bond strength, you get unrealistic values.

And second, parameters like for instance the proof stress can vary by a factor of 100 for the same alloy, depending on work hardening and on its heat treatment, despite the chemical composition stays the same.

For ceramics and semimetals, there is some hope to predict a hardness, but generally brittleness is what define their behaviour in real use, and brittleness is about impossible to predict.

So clearly, this approach is sterile. Alas, we don't have a better theory that would give numerical predictions. Nearly every data available about the "strength" of materials is experimental.