Question

A molecule with the formula AB₂, in which A and B represent different atoms, could have one of three different shapes. Sketch and name the three different shapes that this molecule might have. Give an example of a molecule or ion for each shape.

a) Linear - Example: BeCl₂
b) Trigonal Planar - Example: BF₃
c) Bent (V-shaped) - Example: H₂O
d) Tetrahedral - Example: CH₄

Answer 1

The molecule AB2 can have a linear, bent, or trigonal planar shape depending on the electron pairs around the central atom, with examples being BeCl2, H2O, and BF3 respectively.

Step-by-step explanation:

A molecule with the formula AB2 can have three different shapes based on Valence Shell Electron Pair Repulsion (VSEPR) theory which depends on the number of bonding and non-bonding electron pairs around the central atom.

• Linear: This shape occurs when there are no lone pairs of electrons on the central atom and the two B atoms are 180° apart. Example: BeCl2
• Bent (V-shaped): This shape is seen when there are two bonding pairs and at least one lone pair of electrons on the central atom. Example: H2O
• Trigonal Planar: When there are three bonding pairs and no lone pairs, the atoms lie on a flat plane with 120° between them. Example: BF3

Each shape is characterized by its unique arrangement of electron groups which determine the molecular geometry.