how to determine hybridization
How to determine hybridization
Answer:
To determine the hybridization of a given atom in a molecule, you need to follow a structured approach that involves understanding the molecule’s geometry, the number of atoms bonded to the central atom, and the lone pairs of electrons on the central atom. Here’s a step-by-step approach to determine hybridization:
Solution By Steps:
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Identify the Central Atom:
- The central atom is usually the least electronegative element that isn’t hydrogen.
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Count the Number of Sigma Bonds:
- Count how many sigma (\sigma) bonds are formed by the central atom. Remember, a single bond consists of one sigma bond, a double bond has one sigma bond and one pi bond, and a triple bond has one sigma bond and two pi bonds.
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Count the Lone Pairs:
- Determine the number of lone pairs on the central atom. Each lone pair is counted as an electron domain.
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Calculate the Steric Number:
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The steric number is the sum of the sigma bonds and the lone pairs on the central atom.
\text{Steric Number} = \text{Number of sigma bonds} + \text{Number of lone pairs}
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Determine the Hybridization:
- Use the steric number to determine the hybridization according to the table below:
Steric Number | Hybridization | Geometry |
---|---|---|
2 | sp | Linear |
3 | sp2 | Trigonal planar |
4 | sp3 | Tetrahedral |
5 | sp3d | Trigonal bipyramidal |
6 | sp3d2 | Octahedral |
Examples:
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Molecule: Methane (CH₄):
- Central atom: Carbon (C).
- Number of sigma bonds: 4 (each C-H bond is a sigma bond).
- Number of lone pairs on central atom (C): 0.
- Steric number = 4 sigma bonds + 0 lone pairs = 4.
- Hybridization: sp3.
Methane has a tetrahedral geometry.
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Molecule: Water (H₂O):
- Central atom: Oxygen (O).
- Number of sigma bonds: 2 (each O-H bond is a sigma bond).
- Number of lone pairs on central atom (O): 2.
- Steric number = 2 sigma bonds + 2 lone pairs = 4.
- Hybridization: sp3.
Water has a bent geometry.
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Molecule: Phosphorus pentachloride (PCl₅):
- Central atom: Phosphorus (P).
- Number of sigma bonds: 5 (each P-Cl bond is a sigma bond).
- Number of lone pairs on central atom (P): 0.
- Steric number = 5 sigma bonds + 0 lone pairs = 5.
- Hybridization: sp3d.
Phosphorus pentachloride has a trigonal bipyramidal geometry.
Example Problem:
Problem: Determine the hybridization of the central atom in sulfur hexafluoride (SF₆).
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Central Atom:
- The central atom is sulfur (S).
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Count the Number of Sigma Bonds:
- Sulfur forms six sigma bonds with fluorine atoms.
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Count the Lone Pairs on the Central Atom:
- Sulfur has no lone pairs in SF₆.
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Calculate the Steric Number:
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The steric number is the sum of sigma bonds and lone pairs.
\text{Steric Number} = 6 \ (\text{sigma bonds}) + 0 \ (\text{lone pairs}) = 6
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Determine the Hybridization:
- A steric number of 6 corresponds to sp3d2 hybridization.
Final Answer:
The hybridization of the central atom in sulfur hexafluoride (SF₆) is sp3d2.
By following these steps, you can systematically determine the hybridization of any given atom in a molecule.