Question

What type of central-atom orbital hybridization corresponds to each electron- group arrangement: (a) trigonal planar; (b) octahedral; (c) linear; (d) tetrahedral; (e) trigonal bipyramidal?

Short answer

a) sp^2, b) sp^3d^2, c) sp, d) sp^3, e) sp^3d.

Step-by-step solution

Identify the Electron-Group Arrangement

Understand the geometrical arrangement which is given in each part of the question: (a) trigonal planar, (b) octahedral, (c) linear, (d) tetrahedral, (e) trigonal bipyramidal.

Determine the Number of Electron Groups

Determine the corresponding number of electron groups around the central atom for each arrangement: (a) Trigonal planar: 3 electron groups (b) Octahedral: 6 electron groups (c) Linear: 2 electron groups (d) Tetrahedral: 4 electron groups (e) Trigonal bipyramidal: 5 electron groups

Match Electron Groups to Hybridization

Match the number of electron groups to their respective hybridization states: (a) 3 electron groups correspond to sp^2 hybridization (b) 6 electron groups correspond to sp^3d^2 hybridization (c) 2 electron groups correspond to sp hybridization (d) 4 electron groups correspond to sp^3 hybridization (e) 5 electron groups correspond to sp^3d hybridization

Key concepts

Trigonal Planar Hybridization

Understanding trigonal planar hybridization helps in identifying the shape and bonding of molecules.
This type involves 3 electron groups around the central atom, leading to a 120° bond angle between groups.
One commonly known molecule exhibiting trigonal planar hybridization is boron trifluoride (BF₃).
Here, boron (B) forms three covalent bonds using its three unpaired electrons, resulting in an \( sp^2 \) hybridization state.
The geometry ensures the molecule stays flat and planar.

Octahedral Hybridization

Octahedral hybridization usually involves 6 electron groups or bonding pairs arranged around a central atom.
The bond angles in an octahedral structure are all 90°.
An example of a molecule with octahedral geometry is sulfur hexafluoride (SF₆).
In this case, sulfur uses \( sp^3d^2 \) hybrid orbitals to form six bonds with fluorine atoms.
This arrangement leads to a highly symmetrical structure with minimal repulsion between electron pairs.

Linear Hybridization

Linear hybridization occurs when there are 2 electron groups around a central atom.
This results in a straight-line shape with a bond angle of 180°.
A well-known example is carbon dioxide (CO₂).
The carbon atom in CO₂ forms two double bonds with oxygen atoms using \( sp \) hybrid orbitals.
The linear geometry helps in understanding why CO₂ is non-polar despite its polar bonds.

Tetrahedral Hybridization

Tetrahedral hybridization is a common type involving 4 electron groups around a central atom.
This gives rise to a tetrahedral shape with bond angles of approximately 109.5°.
Methane (CH₄) is a typical example, where carbon forms four single bonds with hydrogen atoms.
The carbon atom uses \( sp^3 \) hybrid orbitals in this configuration.
The tetrahedral arrangement minimizes the repulsion between the bonding pairs, leading to a stable structure.

Trigonal Bipyramidal Hybridization

Trigonal bipyramidal hybridization involves 5 electron groups around a central atom.
The geometry consists of three atoms in a plane (equatorial positions) and two atoms above and below this plane (axial positions).
Phosphorus pentachloride (PCl₅) is a prime example, where phosphorus (P) forms five bonds utilizing \( sp^3d \) hybridization.
The bond angles are 90° between axial and equatorial positions and 120° among the equatorial positions.
This hybridization type showcases unique arrangements and properties in chemical structures.