What is the molecular geometry of sulfur tetrafluoride (SF_4)?

• A. Square planar
• B. Trigonal bipyramidal
• C. Tetrahedral
• D. See-saw

Answer: (D)

Verified step by step guidance

1. Step 1: Determine the Lewis structure of SF_4 by counting the total valence electrons. Sulfur (S) has 6 valence electrons, and each fluorine (F) has 7 valence electrons. Multiply 7 by 4 for the four fluorines and add 6 for sulfur to get the total number of valence electrons.
2. Step 2: Draw the skeletal structure with sulfur as the central atom bonded to four fluorine atoms. Use pairs of electrons to form single bonds between sulfur and each fluorine atom.
3. Step 3: Distribute the remaining electrons to complete the octets of the fluorine atoms first, then place any leftover electrons on the sulfur atom as lone pairs.
4. Step 4: Count the regions of electron density (bonding pairs + lone pairs) around the central sulfur atom. SF_4 has 4 bonding pairs and 1 lone pair, making a total of 5 regions of electron density.
5. Step 5: Use the VSEPR theory to predict the molecular geometry. Five regions of electron density correspond to a trigonal bipyramidal electron geometry. The presence of one lone pair distorts the shape to a 'see-saw' molecular geometry.