Sketch the Lewis Dot Structure for each of the following compounds and state the molecular geometry.

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Sketch the Lewis Dot Structure for each of the following compounds and state the molecular geometry. i. BeF2 ii. BCl3 iii. CCl4 iv. PBr5

The Correct Answer and Explanation is:

Here are the Lewis structures and molecular geometries for each of the compounds you mentioned:

i. BeF2 (Beryllium fluoride)

Lewis Structure:

  • Beryllium (Be) is in Group 2 and has 2 valence electrons.
  • Fluorine (F) is in Group 17 and has 7 valence electrons each.
  • Be will bond with two fluorine atoms, and each fluorine will form a single bond with Be, using one of their lone pairs. Each fluorine will also have three lone pairs remaining.

The Lewis structure of BeF2 is:

rCopyEdit   F—Be—F
  • Beryllium is the central atom, and each fluorine is attached by a single bond.

Molecular Geometry:

  • The molecular geometry is linear.
  • Be has two bonding pairs and no lone pairs. According to the VSEPR theory, this results in a 180° bond angle.

ii. BCl3 (Boron trichloride)

Lewis Structure:

  • Boron (B) is in Group 13 and has 3 valence electrons.
  • Chlorine (Cl) is in Group 17 and has 7 valence electrons each.
  • Boron will form three single bonds with three chlorine atoms, and each chlorine will have three lone pairs remaining.

The Lewis structure of BCl3 is:

lessCopyEdit    Cl
     |
  Cl—B—Cl
  • Boron is the central atom, and each chlorine is bonded to it by a single bond.

Molecular Geometry:

  • The molecular geometry is trigonal planar.
  • Boron has three bonding pairs and no lone pairs. This gives a 120° bond angle between the chlorine atoms.

iii. CCl4 (Carbon tetrachloride)

Lewis Structure:

  • Carbon (C) is in Group 14 and has 4 valence electrons.
  • Chlorine (Cl) is in Group 17 and has 7 valence electrons each.
  • Carbon will form four single bonds with four chlorine atoms, and each chlorine will have three lone pairs remaining.

The Lewis structure of CCl4 is:

markdownCopyEdit       Cl
       |
  Cl—C—Cl
       |
       Cl
  • Carbon is the central atom, and each chlorine is bonded to it by a single bond.

Molecular Geometry:

  • The molecular geometry is tetrahedral.
  • Carbon has four bonding pairs and no lone pairs. This gives a 109.5° bond angle between the chlorine atoms.

iv. PBr5 (Phosphorus pentabromide)

Lewis Structure:

  • Phosphorus (P) is in Group 15 and has 5 valence electrons.
  • Bromine (Br) is in Group 17 and has 7 valence electrons each.
  • Phosphorus will form five single bonds with five bromine atoms, and each bromine will have three lone pairs remaining.

The Lewis structure of PBr5 is:

lessCopyEdit       Br
       |
  Br—P—Br
       |
  Br—P—Br
       |
       Br
  • Phosphorus is the central atom, and each bromine is bonded to it by a single bond.

Molecular Geometry:

  • The molecular geometry is trigonal bipyramidal.
  • Phosphorus has five bonding pairs and no lone pairs. The bond angles are 90° between atoms in the axial positions and 120° between atoms in the equatorial positions.

Summary of Molecular Geometries:

  • BeF2: Linear (180° bond angle)
  • BCl3: Trigonal planar (120° bond angle)
  • CCl4: Tetrahedral (109.5° bond angle)
  • PBr5: Trigonal bipyramidal (90° and 120° bond angles)

These geometries are determined by the number of bonding pairs and lone pairs around the central atom, as predicted by VSEPR theory.

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