How to determine hybridization

General
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how to determine hybridization

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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:

  1. Identify the Central Atom:

    • The central atom is usually the least electronegative element that isn’t hydrogen.

  2. 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.

  3. Count the Lone Pairs:

    • Determine the number of lone pairs on the central atom. Each lone pair is counted as an electron domain.

  4. Calculate the Steric Number:

    • 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}

  5. 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:

  1. 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.

  2. 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.

  3. 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).

  1. Central Atom:

    • The central atom is sulfur (S).

  2. Count the Number of Sigma Bonds:

    • Sulfur forms six sigma bonds with fluorine atoms.

  3. Count the Lone Pairs on the Central Atom:

    • Sulfur has no lone pairs in SF₆.

  4. Calculate the Steric Number:

    • The steric number is the sum of sigma bonds and lone pairs.

      \text{Steric Number} = 6 \ (\text{sigma bonds}) + 0 \ (\text{lone pairs}) = 6

  5. 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.