SF4 (Sulfur tetrafluoride) Lewis Structure
SF4 (Sulfur tetrafluoride) molecule contains one sulfur atom and four fluorine atoms. In SF4 lewis structure, each fluorine atom has made single bonds with center sulfur. Also, there is a lone pair on sulfur atom and three lone pairs on each fluorine atom. In this tutorial, we will learn how to draw the lewis structure of SF4 step by step.
SF4 lewis structure
In this lewis structure of SF4, center sulfur atom has made four single bonds with four fluorine atoms. There is a lone pair on center sulfur atom and each fluorine atom also has three lone pairs. Also, there are no charges on atoms in SF4 lewis structure and no overall charge in the molecule.
Steps of drawing lewis structure of SF4
There are general guidelines to draw a lewis structure of a molecule. Number of steps can be changed according the complexity of the molecule or ion. Now, we are going to study study each step of drawing the lewis structure of SF4.
- Find total number of electrons of the valance shells of sulfur and fluorine atom
- Total electrons pairs existing as lone pairs and bonds
- Center atom selection
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Total number of electrons of the valance shells of SF4
There are only two elements in Sulfur tetrafluoride; sulfur and fluorine. Sulfur is a group VIA element in the periodic table and has six electrons in its last shell (valence shell). Fluorine is a group VIIA element in the periodic table and contains seven electrons in its last shell.
- valence electrons given by sulfur atom = 6 * 1 = 6
- valence electrons given by fluorine atoms = 7 * 4 = 28
- Total valence electrons = 6 + 28 = 34
Total valence electrons pairs
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, SF4, Total pairs of electrons are seventeen (34/2) in their valence shells.
Selection of center atom of SF4
There are requirements to be the center atom in a molecule. Having a high valence and being the most electropositive atom are the most important facts to be the center atom. In SF4, there are only two elements to select the center atom. in SF4
- Sulfur's maximum valence is 6. Fluorine's maximum valence is 1. From that fact, Sulfur has the high priority to be the center atom.
- Phosphorus's and boron's electronegativity values are 2.1 and 4.0 respectively. in this case, phosphorus is more electropositive than fluorine. In this occasion too, fluorine has the highest chance to be the center atom.
- From above 1 and 2 facts, it is clear that sulfur atom should be the center atom.
Mark lone pairs on atoms of SF4
After determining the center atom and sketch of SF4 molecule, we can start to mark lone pairs on atoms. Remember that, there are total of seventeen electron pairs to mark as bonds and lone pairs in SF4 molecule.
- There are already 4 sigma bonds in the above drawn sketch (4 S-F bonds). Now only thirteen (17-4=13) lone pairs are remaining to mark on sulfur and fluorine atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms (fluorine). Then, mark lone pairs on fluorine atoms. Each outside fluorine atom will take 3 lone pairs. Now, 12 electron pairs are marked as lone pairs on outside fluorine atoms. So, now there are only one lone pair to mark on sulfur atom.
Mark charges on atoms and reduce charges to obtain most stable lewis structure
There are no charges on any of atoms in our structure of SF4. Therefore, we don't need to reduce charges to get the most stable structure. That means, we have already obtained the lewis structure of SF4.
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