[oilypiggy]

Hi Guys, can anyone help with this question?
Using the VSEPR model, the electron-domain geometry of the central atom in NO2- is _______
a) Linear
b)Trigonal Planar
c) Tetrahedral
d)Trigonal Bipyramidal
e)Octahedral

Thanks!

[sjb]

What are your thoughts? How many electron pairs are there around the central atom?

[ChargePositive]

Are you able to draw out Lewis structure for the molecule? If you are, classifying the shape is easy, and goes by the number of lone pairs of electrons and bonded pairs of electrons. You can always look up a VSEPR Chart that tells you what shape the molecule will be based on the electron pairs.

[oilypiggy]

I'm unsure of its 3 or 4 as i dont knwo if the double bond counts

[AWK]

both wrong
You must draw the Lewis structure correctly. Double or triple bonds in the Lewis structure count as "one pair" of electrons for the purpose of establishing the electron pair geometry.

[oilypiggy]

Doesn't the lone electron pair count as a domain too

[AWK]

The VSEPR method consists of several rules. I indicated only one that you omitted, indicating an incorrect answer This rule only indicates how to treat multiple bonds, and does not say anything about non-bonding electron pairs or individual non-bonding electrons. Without taking all rules into account, step by step, you will not get a correct answer.

[oilypiggy]

I am still incredibly lost, I count 3 electron domains still

[AWK]

So far correct. This excludes c, d, and e.

[oilypiggy]

Isn't linear 2 electron domains as well

[AWK]

So the problem is solved.

[oilypiggy]

I'm confused, what are you saying the answer is?

[AWK]

 

I count 3 electron domains still

[oilypiggy]

Isn't trigonal planar for a molecule with no lone pairs though

[mjc123]

Are you confusing molecular geometry with electron-domain geometry?