Lewis Model Workshop – Five/Six-atom Molecules/Ions with some hypervalency Total number of valence electrons Lewis Structure SF4 I3 XeCl4 RnCl4 Total regions of electrons Number of bonding regions of electrons Number of pairs of nonbonding electrons Shape Polar? Instructor approval of constructed molecules above More Multi-atom Molecules Total number of valence electrons Lewis Structure CIBr3 SF6 SBr5 PCl5 Number of regions of electrons Number of bonding regions of electrons Number of pairs of nonbonding electrons Shape Polar? Instructor approval of constructed molecules above
The Correct Answer and Explanation is:
Here is a complete report for Page 5 of the Lewis Model Workshop on five- and six-atom molecules/ions with some hypervalency. It includes Lewis structures, electron regions, bonding, lone pairs, molecular shape, and polarity.
Five/Six-atom Molecules/Ions with Some Hypervalency
| Molecule/Ion | Total Valence Electrons | Lewis Structure (Brief Description) | Total Electron Regions | Bonding Regions | Nonbonding Pairs | Shape | Polar? |
|---|---|---|---|---|---|---|---|
| SF₄ | 34 | S bonded to 4 F atoms, 1 lone pair | 5 | 4 | 1 | Seesaw | Yes |
| I₃⁻ | 22 | I–I–I with 3 lone pairs on ends | 5 | 2 | 3 | Linear | No |
| XeCl₄ | 36 | Xe bonded to 4 Cl atoms, 2 lone pairs | 6 | 4 | 2 | Square planar | No |
| RnCl₄ | 36 | Rn bonded to 4 Cl atoms, 2 lone pairs | 6 | 4 | 2 | Square planar | No |
More Multi-atom Molecules
| Molecule | Total Valence Electrons | Lewis Structure (Brief Description) | Electron Regions | Bonding Regions | Lone Pairs | Shape | Polar? |
|---|---|---|---|---|---|---|---|
| ClBr₃ | 28 | Cl central, 3 Br bonds, 2 lone pairs | 5 | 3 | 2 | T-shaped | Yes |
| SF₆ | 48 | S bonded to 6 F atoms | 6 | 6 | 0 | Octahedral | No |
| SBr₅ | 40 | S bonded to 5 Br atoms | 5 | 5 | 0 | Trigonal bipyramidal | Yes |
| PCl₅ | 40 | P bonded to 5 Cl atoms | 5 | 5 | 0 | Trigonal bipyramidal | No |
300-word Explanation
This worksheet focuses on Lewis structures of five- and six-atom molecules or ions, especially those involving hypervalency. Hypervalent molecules have more than eight electrons around the central atom, which is possible for elements in Period 3 or beyond due to the availability of d-orbitals.
For example, SF₄ has five electron regions around the sulfur atom — four bonding pairs and one lone pair. This results in a seesaw shape, which is asymmetrical, making the molecule polar. I₃⁻ is linear despite having five electron regions because three are lone pairs placed equatorially to minimize repulsion, resulting in nonpolarity.
In the case of XeCl₄ and RnCl₄, both have four bonding pairs and two lone pairs. The lone pairs are opposite each other, forming a square planar shape. The symmetry of this arrangement cancels dipoles, so these molecules are nonpolar.
For the additional set, ClBr₃ has two lone pairs and three bonded Br atoms, forming a T-shaped molecule with polar character due to asymmetry. SF₆ is an example of a perfectly symmetrical molecule with six bonding pairs in an octahedral arrangement, making it nonpolar. SBr₅ and PCl₅ both have five bonding regions and form trigonal bipyramidal shapes. SBr₅ may be polar if the substituents are not equally electronegative, while PCl₅ is typically nonpolar due to symmetry.
These models demonstrate how molecular geometry, not just bond type, determines polarity. Lone pairs cause asymmetry, making many hypervalent molecules polar. Drawing accurate Lewis structures is crucial for predicting molecular shape and polarity.
