1) I think there is a hydrogen atom missing in the molecule drawing.
If you calculate the degree of unsaturation http://en.wikipedia.org/wiki/Degree_of_unsaturation
, you get:
1+[5*(4-2)+1*(3-2)+1*(2-2)+6*(1-2)]/2 = 3.5
It is not an integer number, which indicates you have an unpaired electron. So, either this molecule is a radical, or there is one hydrogen missing somewhere.
Furthermore, the answer given in the book is 11,2. So they say there are 13 bonds in total, considering both single and multiple bonds. But, one can only see 12 bonds in the drawing. One hydrogen is missing.
If you add one hydrogen to the molecule, the degree of unsaturation becomes 3. This means you have 3 unsaturations in total. What do I mean by unsaturation:
- double bonds count for 1 unsaturation each
- triple bonds count for 2 unsaturations each
- cycles count for 1 unsaturation each
* Let's add one hydrogen to the oxygen, so it forms an alcohol group. In order to have the octet rule true for each carbon and nitrogen atom, one must add 1 double bond and 1 triple bond:
The unsaturation is 3 indeed, as we had calculated.
* Let's add the hydrogen on the carbon next to the CH3:
In both cases, the answer to your question is 11,2.
It seems to me that structure b is correct.
is constituted from I2
(where each iodine has 3 lone pairs) + I-
(which has 4 lone pairs) where I-
gives one lone pair to I2
to form a covalent bond. So, all iodine atoms have three lone pairs each. And the molecule is linear http://en.wikipedia.org/wiki/Triiodide