What is the molecular geometry of BeCl2? a. Linear b. trigonal planar c. tetrahedral d. bent e, trigonal pyramid
The Correct Answer and Explanation is :
The correct answer is a. Linear.
Explanation:
The molecular geometry of beryllium chloride (BeCl₂) can be understood using the Valence Shell Electron Pair Repulsion (VSEPR) theory, which predicts the geometry of molecules based on the repulsion between electron pairs around the central atom.
- Central Atom and Electron Configuration:
- Beryllium (Be) is the central atom in BeCl₂.
- Its electronic configuration is 1s22s21s^2 2s^2, and in BeCl₂, beryllium forms two covalent bonds with two chlorine atoms by using its two valence electrons. It does not have any lone pairs of electrons remaining on the central atom after bonding.
- Bonding and Steric Number:
- The steric number of the central atom is the sum of bonded atoms and lone pairs of electrons.
- For BeCl₂, there are 2 bonded atoms (Cl atoms) and 0 lone pairs on Be. Thus, the steric number is 2.
- VSEPR Geometry Prediction:
- When the steric number is 2 and there are no lone pairs on the central atom, the molecule adopts a geometry that minimizes electron-pair repulsion by arranging the bonded atoms as far apart as possible.
- The optimal geometry for two regions of electron density is linear.
- Bond Angles:
- In a linear geometry, the bond angle between the two chlorine atoms is 180∘180^\circ.
- Hybridization:
- The beryllium atom in BeCl₂ undergoes sp hybridization, forming two sp orbitals that overlap with the p orbitals of the chlorine atoms to create sigma bonds.
Summary:
BeCl₂ has a linear molecular geometry because there are no lone pairs on the central beryllium atom, and the bonded chlorine atoms are positioned to minimize repulsion, leading to a 180∘180^\circ bond angle.