Consider the Lewis structure for SF6 There are a total of valence electrons. There are bonding electrons, non-bonding electrons, and lone pairs of electrons.
Question 3 1 pts Using VSEPR theory, a molecule with the general formula AX Ex (A is the central atom, X is the bonded atom and E is a lone pair of electrons), how many regions of electron density around the central atom in AXs? (the E subscript is zero) [Select] axs will have what kind of electron-group arrangement? [select] axs will have what kind of molecular shape?
The Correct Answer and Explanation is:
Question 2: Lewis Structure of SF₆
- Total valence electrons: 48
- Bonding electrons: 12
- Non-bonding electrons: 36
- Lone pairs of electrons: 18
Question 3: AX₆ Molecule Based on VSEPR Theory
- Regions of electron density: 6
- Electron-group arrangement: Octahedral
- Molecular shape: Octahedral
Explanation (300+ words)
Question 2: Lewis Structure of SF₆
Sulfur hexafluoride (SF₆) is a molecule consisting of one sulfur atom (S) and six fluorine atoms (F). To determine the number of valence electrons:
- Sulfur (group 16) has 6 valence electrons.
- Fluorine (group 17) has 7 valence electrons each × 6 = 42 valence electrons.
Total = 6 (S) + 42 (F) = 48 valence electrons.
In the Lewis structure:
- Sulfur forms six single bonds with each fluorine atom.
- Each bond contains 2 electrons, so 6 bonds × 2 = 12 bonding electrons.
- The remaining 36 electrons (48 total – 12 bonding) are assigned as non-bonding electrons (lone pairs) on the fluorine atoms.
- Each fluorine gets 3 lone pairs (6 electrons), and 6 fluorines × 6 electrons = 36 non-bonding electrons.
- These 36 non-bonding electrons are grouped into 18 lone pairs.
Question 3: AX₆ Molecule Using VSEPR Theory
VSEPR (Valence Shell Electron Pair Repulsion) theory helps predict molecular geometry by minimizing repulsions between regions of electron density (bonds or lone pairs) around a central atom.
For an AX₆ molecule:
- A is the central atom.
- X₆ indicates six bonded atoms.
- There are no lone pairs on the central atom (E = 0).
This gives six regions of electron density, all bonding pairs. To minimize repulsion, these arrange themselves in an octahedral geometry.
- Electron-group arrangement: Octahedral
- Molecular shape: Octahedral (since there are no lone pairs altering the shape)
- Bond angles: 90° between all adjacent atoms.
Examples of AX₆ molecules include SF₆, where sulfur is bonded to six fluorine atoms symmetrically. The octahedral shape is highly symmetrical and stable, which is why SF₆ is used as an inert electrical insulator.
In summary:
- SF₆ has 48 valence electrons: 12 bonding, 36 non-bonding.
- AX₆ molecules have 6 electron regions, an octahedral geometry, and an octahedral molecular shape.