Saved Draw the Lewis Structure of SF4. Determine the ÉG and MG. Is the molecule Polar, Nonpolar or Ionic? If the molecule is polar show the dipole moment as a arrow on or near the structure.
The Correct Answer and Explanation is:
Lewis Structure of SF₄:
- Count Valence Electrons:
- Sulfur (S) is in Group 16, so it has 6 valence electrons.
- Fluorine (F) is in Group 17, so each fluorine has 7 valence electrons.
- Total valence electrons: 6+4×7=346 + 4 \times 7 = 346+4×7=34 valence electrons.
- Arrange the Atoms:
- Sulfur is the central atom, surrounded by four fluorine atoms.
- Bonding:
- Each F atom will form a single bond with the sulfur atom. This uses 4 electrons (one per F-S bond), leaving 34−8=2634 – 8 = 2634−8=26 electrons.
- Distribute Remaining Electrons:
- Place the remaining 26 electrons as lone pairs on the fluorine atoms. Each fluorine needs 6 electrons to complete its octet, so 6 electrons per fluorine are placed as lone pairs, using 4×6=244 \times 6 = 244×6=24 electrons, leaving 2 electrons.
- Place Remaining Electrons:
- The remaining 2 electrons are placed as a lone pair on the sulfur atom.
Now the Lewis Structure looks like this:
rCopyEdit F
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F - S - F
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F
With two lone pairs on sulfur.
Electron Geometry (ÉG):
The electron geometry considers all bonding and lone pairs around the central atom. In SF₄, there are 4 bonding pairs (F atoms) and 1 lone pair on sulfur. This gives a trigonal bipyramidal geometry, with the lone pair occupying an equatorial position.
Molecular Geometry (MG):
The molecular geometry focuses only on the positions of the atoms (ignoring lone pairs). Since there are 4 fluorine atoms and 1 lone pair, the molecular geometry is a seesaw shape, characteristic of a trigonal bipyramidal arrangement with one lone pair.
Polarity:
Since SF₄ has a seesaw shape, the dipole moments of the bonds do not cancel out. The fluorine atoms, being more electronegative than sulfur, create a dipole pointing toward each fluorine. As a result, the molecule has an overall net dipole moment, making it polar.
Dipole Moment:
To show the dipole moment, we would draw arrows pointing toward each fluorine atom from the sulfur atom.
Conclusion:
- Electron Geometry: Trigonal bipyramidal
- Molecular Geometry: Seesaw
- Polarity: Polar (with a net dipole moment pointing toward the fluorine atoms)
