Posted by Deneb on April 29, 2009, at 19:33:21
In reply to chemistry help, posted by alexandra_k on April 29, 2009, at 13:19:28
> So I thought I was getting the difference between ionic / extravalent bonds and covalent bonds but now I'm confused again...
>
> NaCl is an example of an extravalent bond because Sodium DONATES one electron to Clorine to satisfy the octet rule.
> H2 is an example of a single covalent bond because two elements of Hydrogen SHARE one electron (one pair of electrons) to satisfy the octet rule.
> C02 is an example of a double covalent bond because two elements of oxygen SHARE two pairs of electrons with carbon to satisfy the octet rule.
> H20 is an example of a double covalent bond because two elements of Hydrogen SHARE two pairs of electrons to satisfy the octet rule.
> But then apparently 'water molecules dissociate continually in a reversible reaction to form hydrogen ions (H+ and hydroxide ions (OH-):
>
> H20 <--> H+ + OH-
>
> Hmm.
>
> But then does H2 similarly dissociate continually in a reversible reaction to form hydrogen ions (H+ and H-)?No, I have forgotten a lot of basic chemistry, but no, H2 does not dissociate, the bonds are too strong. H- is not possible unless it is an ionic bond with something like NaH. H2 is actually very stable and is a gas.
> And then do carbon dioxide molecules dissociate continually in a reversible reaction to form carbon ions and hydrogen ions (C- and 2O+)?
No, definitely no. The bonds are too strong. Carbon dioxide is a covalently bonded molecule. Two carbon ions are extremely unstable, and I don't think a positively charged oxygen is possible.
>
> If so... Then I lose the distinction between extravalent bonds and covalent bonds (donating vs sharing).
>
> Does this have something to do with problems locating electrons in clouds?
>
> Is this basically an issue of 'don't worry about it just keep going and learn about carbs / proteins / lipids'?
poster:Deneb
thread:893467
URL: http://www.dr-bob.org/babble/social/20090421/msgs/893491.html