Hybridization and Geometry of OH- Ion

So, in summary, the hydroxide ion, OH-, has a tetrahedral geometry shape and the oxygen atom uses sp3 hybridization to accommodate the bonding and nonbonding domains.
  • #1
lkh1986
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Question: State the hybridization used and the molecular geometry shape of hydroxide ion, OH-.

Okay, so I draw out the Lewis structure, where there are 6 electrons (3 lone pairs) around the O atom, which is bonded to the H atom. So, I think base on the 3 nonbonding domains and 1 bonding domain, I think the shape is tetrahedral, but it seems weird to me, because I think it may be linear.

Then, regarding the hybridization, I think the O atom uses sp3 hybridization, but then again, I think there is no hybridization involved, because O can use the remaining empty 2s orbital to bond to the only one electron from H atom.

Which one is the correct one? :confused:
 
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  • #2
lkh1986 said:
Question: State the hybridization used and the molecular geometry shape of hydroxide ion, OH-.

Okay, so I draw out the Lewis structure, where there are 6 electrons (3 lone pairs) around the O atom, which is bonded to the H atom. So, I think base on the 3 nonbonding domains and 1 bonding domain, I think the shape is tetrahedral, but it seems weird to me, because I think it may be linear.
When you are asked for the shape of the molecule/ion, you are asked to describe the relative positions of the atoms, not the relative positions of the orbitals. If you were going to describe the geometry of the orbitals (instead of the geometry of the atoms) then you'd say NH3 was tetrahedral (instead of a trigonal pyramid).

Then, regarding the hybridization, I think the O atom uses sp3 hybridization, but then again, I think there is no hybridization involved, because O can use the remaining empty 2s orbital to bond to the only one electron from H atom.
What empty 2s orbital? Is there an empty 2s in oxygen?
 
  • #3
First: Identify the number of valence electrons present in the total compound.
Second: Draw the Lewis structure
Third: Remember that though the electron configuration maybe tetrahedral that does not mean that the whole molecule will have that shape. You must look at the total 'effective bonds'.

I agree with Gokul, there are no empty 2s orbitals for O. Look at everything again. Hope that helps.
 
  • #4
Gokul43201 said:
What empty 2s orbital? Is there an empty 2s in oxygen?

Oh, sorry, typo there. I mean 2p orbital.
 
  • #5
Okay, that makes more sense. But now, it seems you need to understand how hybridization works.

You could as well ask a similar question regarding the H2O structure. After all, you could just as well argue that the 2 vacancies in the 2p orbitals can be used to accommodate the electrons from the 2 H atoms. So, the exact same argument as the one above, would lead you to conclude that H2O requires no hybridization either.

If that were true, why then, is the H-O-H bond angle much closer to 109 than it is to 90 deg? Clearly, hybridization is involved in H2O, as it will be in the case of OH-. The reason that hybrid orbitals are closer to reality is due to the reduction in energy that results from hybridization.
 

1. What is hybridization and how does it relate to OH- ions?

Hybridization is the mixing of atomic orbitals to form new hybrid orbitals. OH- ions have hybridization involving one s orbital and one p orbital, resulting in a bent shape.

2. What is the geometry of an OH- ion?

The geometry of an OH- ion is bent, with a bond angle of approximately 109.5 degrees.

3. What are the hybrid orbitals involved in the formation of OH- ions?

OH- ions have sp3 hybridization, involving one s orbital and three p orbitals.

4. How does the hybridization of an OH- ion affect its polarity?

The hybridization of an OH- ion results in a polar molecule due to the asymmetrical distribution of electron density caused by the bent shape.

5. What is the significance of the hybridization and geometry of OH- ions in chemical reactions?

The hybridization and geometry of OH- ions play a crucial role in determining the chemical properties and reactivity of the ion. For example, the bent shape allows for a greater degree of flexibility in bonding, making OH- ions more reactive in chemical reactions.

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