Question

1. for one of the following molecules/ions:

i) draw the lewis structure
ii) predict the electron group arrangement and shape using vsepr.
iii) indicate and justify the overall polarity of the molecule/ion
iv) list the intermolecular forces (imf’s) that would be present
a) pcl₅ or b) no₃⁻

Explanation:

Step1: Determine valence electrons for PCl₅

Phosphorus (P) has 5 valence electrons and each chlorine (Cl) has 7 valence electrons. For PCl₅, total valence electrons = 5+(5×7)=40.

Step2: Draw Lewis structure for PCl₅

P is the central atom. Connect P to 5 Cl atoms with single - bonds. Each Cl has 3 lone - pairs to complete its octet.

Step3: Predict electron - group arrangement and shape using VSEPR

The central P atom has 5 bonding pairs and 0 lone - pairs. The electron - group arrangement is trigonal bipyramidal and the molecular shape is also trigonal bipyramidal.

Step4: Determine polarity of PCl₅

The P - Cl bonds are polar due to electronegativity difference. But the trigonal bipyramidal geometry of PCl₅ is symmetric, so the bond dipoles cancel out and the molecule is non - polar.

Step5: Identify intermolecular forces

Since PCl₅ is non - polar, the only intermolecular forces present are London dispersion forces.

Answer:

i) Lewis structure: P is in the center with 5 single bonds to Cl atoms, and each Cl has 3 lone - pairs.
ii) Electron - group arrangement: trigonal bipyramidal; Molecular shape: trigonal bipyramidal
iii) Polarity: Non - polar. Justification: Symmetric trigonal bipyramidal geometry causes bond dipoles to cancel.
iv) Intermolecular forces: London dispersion forces