Why the bond angle of methane is 109 instead of 90?

In summary, the sp3 hybrid orbitals form a bond angle of 109 degrees due to the tetrahedral shape of molecules in 3D space, which allows for minimized repulsion and increased stability. This is in contrast to a bond angle of 90 degrees, which would result in a less stable molecule. Additionally, valence shell theory is not practical for real-world applications.
  • #1
scientist91
133
0
I know that the sp3 hybrid orbitals form 109 angle, but why the angle is not 90. If the angle is 109 the repulsion is minimized or what? Show some comparations. Thank u.
 
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  • #2
I believe your problem lies in the fact that you are only looking in two dimensions. What orbital theory are you using? Valence shell theory is useless for all practical applications anyway.
 
  • #3
3 Dimensions

Indeed, in 3d space four points equally spaced around a center point form a tetrahedron, not a square, hence your bond angle of 109.5 degrees.
 
  • #4
methane consists of four bonded pairs, i.e 4 C-H bonds. So as to minimize repulsion, the molecule adopts a tetrahedral shape, hence bond angle becomes 109.5. with bond angle of 90, the molecule would not be very stable.
 

1. Why is the bond angle of methane not a perfect 90 degrees?

The bond angle of methane is 109.5 degrees, not 90 degrees, due to the repulsion between the bonding and non-bonding electron pairs on the central carbon atom. This repulsion causes the molecule to adopt a tetrahedral shape, with bond angles of approximately 109.5 degrees.

2. How does the shape of methane affect its properties?

The tetrahedral shape of methane allows for equal distribution of charge and results in a nonpolar molecule. This makes methane relatively unreactive and insoluble in water.

3. Is the bond angle of methane influenced by external factors?

No, the bond angle of methane is not affected by external factors such as temperature or pressure. It is solely determined by the repulsion between the electron pairs on the central carbon atom.

4. Are there any exceptions to the 109.5 degree bond angle in methane?

In some cases, the bond angle in methane may deviate slightly from 109.5 degrees due to the presence of different substituents or steric hindrance. However, the overall tetrahedral shape is still maintained.

5. How is the bond angle of methane experimentally determined?

The bond angle of methane can be measured using techniques such as X-ray crystallography or molecular orbital calculations. These methods involve analyzing the molecular structure and the distances between atoms in the molecule.

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