Molecular Orbital Theory problem

In summary, Molecular Orbital Theory is a model used to describe the electronic structure of molecules by combining atomic orbitals to create molecular orbitals. It differs from Valence Bond Theory in that it considers the entire molecule as a whole and describes bonding as occurring between two specific atoms. The energy levels, or molecular orbitals, in Molecular Orbital Theory dictate the stability and reactivity of a molecule. Bonding and antibonding orbitals are formed by constructive and destructive interference, respectively. However, this theory has limitations as it assumes delocalized electrons, does not account for electron-electron repulsion, and is only applicable to small molecules.
  • #1
ultimateguy
125
1
According to molecular orbital theory, which of the following species is the most likely to exist?

a) [tex]H_{2}^{-2}[/tex]
b) [tex]He_{2}[/tex]
c) [tex]Li_{2}[/tex]
d) [tex]Li_{2}^{-2}[/tex]
e) [tex]Be_{2}[/tex]

I think the answer is c), due to it having a bond order of 1, but I just wanted to make sure.
 
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  • #2
The point here is probably to have you assess the respective diatomic compound given form (e.g. ion with a 2- charge) with other possibly more stable electron counts. For instance if you find that H2 is more stable then H2-, then there's an incentive to browse some of the other choices.
 
  • #3
ultimateguy said:
According to molecular orbital theory, which of the following species is the most likely to exist?

a) [tex]H_{2}^{-2}[/tex]
b) [tex]He_{2}[/tex]
c) [tex]Li_{2}[/tex]
d) [tex]Li_{2}^{-2}[/tex]
e) [tex]Be_{2}[/tex]

I think the answer is c), due to it having a bond order of 1, but I just wanted to make sure.
That's correct. All the others have bond order 0.
 

1. What is Molecular Orbital Theory?

Molecular Orbital Theory is a model used to describe the electronic structure of molecules. It combines the atomic orbitals of individual atoms to create molecular orbitals, which represent the probability of finding an electron in a particular region of space.

2. How does Molecular Orbital Theory differ from Valence Bond Theory?

Molecular Orbital Theory considers the entire molecule as a whole, while Valence Bond Theory focuses on the overlap of atomic orbitals between two atoms. Molecular orbitals are delocalized and extend over the entire molecule in Molecular Orbital Theory, while Valence Bond Theory describes bonding as occurring between two specific atoms.

3. What is the significance of the energy levels in Molecular Orbital Theory?

The energy levels, or molecular orbitals, in Molecular Orbital Theory dictate the stability and reactivity of a molecule. Lower energy levels are more stable, and electrons will fill these levels before moving to higher energy levels.

4. How are bonding and antibonding orbitals formed in Molecular Orbital Theory?

In Molecular Orbital Theory, bonding orbitals are formed by constructive interference of atomic orbitals, while antibonding orbitals are formed by destructive interference. This results in a lower energy bond between atoms for bonding orbitals, and a higher energy region where no bond exists for antibonding orbitals.

5. What are the limitations of Molecular Orbital Theory?

Molecular Orbital Theory assumes that electrons are delocalized and can move freely throughout the molecule, which may not always be the case. It also does not account for the repulsion between electrons, known as electron-electron repulsion, which can affect the stability and shape of molecules. Additionally, Molecular Orbital Theory is only applicable to molecules with a small number of atoms, as the calculations become more complex with larger molecules.

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