-3
$\begingroup$

I'm a little confused studying reaction mechanics and I saw this, where does the water electrons go when the bond is formedenter image description here

I mean, the carbocation needs two more electrons to get its octect filled and the oxygen in water has 2 lone pairs, when the bond is formed, I think one oxygen's lone pair is used. And now the molecule has one lone pair.

Improve this question
$\endgroup$
5
  • 2
    $\begingroup$ Everything you say about octets and lone pairs is true, so what's the question? The whole thing has got to remain positively charged, because charge can't just go nowhere. $\endgroup$
    – Ivan Neretin
    Commented May 30, 2017 at 9:39
  • $\begingroup$ I wonder if by the water providing the necesary electrons, doesn't the molecule become neutral? $\endgroup$
    – Pablo Castro Roldan
    Commented May 30, 2017 at 9:42
  • 1
    $\begingroup$ Ever heard about the charge conservation law? The whole thing (I mean, the carbocation and the water molecule) was positively charged; it totally can't just up and become neutral. $\endgroup$
    – Ivan Neretin
    Commented May 30, 2017 at 9:47
  • 1
    $\begingroup$ count all electrons and protons on the left, than count all protons and electrons on the right. $\endgroup$
    – user37142
    Commented May 30, 2017 at 10:29
  • $\begingroup$ Oh Didn't know water was positively charged, I thought it was neutral, now I get it, thanks mate. $\endgroup$
    – Pablo Castro Roldan
    Commented May 30, 2017 at 21:38

1 Answer 1

Reset to default
0
$\begingroup$

For most of organic chemistry reactions, octet rule is followed (notable exceptions are carbenes and nitrenes). The octet rule states that atoms are stable when they are surrounded by exactly 8 electrons (for hydrogen, it's two).

Oxygen has 6 valence electrons in atomic state. The net charge on the atom is zero.

Oxygen shares its electrons with other atoms to obtain an octet configuration. For example in a water molecule, water shares one of its electron with hydrogen. By doing so, oxygen can get the hydrogen atom's electron in return. There are 4 bonding electrons (2 $\ce{-OH}$ bonds) and 4 lone pairs on the oxygen. This gives oxygen an octet configuration around the atom. The oxygen owns 4 of its lone pairs and half of the bonding pairs (2 in this case). It has 6 electrons. A neutral oxygen atom owns 6 electrons.

Consider the case you have shown. There are 3 bond pairs (6 bonding electrons: two $\ce{-OH}$ bonds and one $\ce{-OC}$ bond) and one lone pair.

The oxygen has a total of 8 electrons surrounding it. The octet rule is satisfied. However, it does not own 6 electrons. It owns the lone pair (2 electrons) and half of the bonding electrons, i.e: 3. You get a total of 5 electrons. A neutral oxygen molecule owns 6 electrons. As the atom is one short of an electron, it is unit positively charged.

Improve this answer
$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.