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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: bb on September 30, 2009, 09:50:27 PM

Title: what is the shape of OH2-?
Post by: bb on September 30, 2009, 09:50:27 PM

i have no idea.. plzz help? is it bent?

Title: Re: what is the shape of OH2-?
Post by: nj_bartel on September 30, 2009, 11:14:54 PM

Sounds like an impossible structure to me

Title: Re: what is the shape of OH2-?
Post by: cth on October 01, 2009, 07:55:52 AM

I did a small Hartree-Fock computation on H₂O and H₂O^-.

For H₂O: O-H distance is 0,95Å and H-O-H angle 105,5 (compare with measured distance 0,9584Å and angle 104,45)
For H₂O^-: O-H distance is 1,03Å and H-O-H angle 99,9

The extra electron goes into an anti-bonding orbital which push the two hydrogen atoms closer to one another. Not surprisingly, this anion is not stable.

Title: Re: what is the shape of OH2-?
Post by: sjb on October 01, 2009, 08:01:09 AM

Quote from: bb on September 30, 2009, 09:50:27 PM

i have no idea.. plzz help? is it bent?

Do you mean OH₂^- (water, with an additional electron)? or OH^2- (hydroxide, also with an addtional electron)? How many atoms are there in your ion?

Title: Re: what is the shape of OH2-?
Post by: cth on October 01, 2009, 11:33:35 AM

Yes, the title is confusing but I guess he meant H₂O^-.

There is no sense to ask the geometry and angle of a diatomic compound which would necessarily be linear.