Arsenic trifluoride - AsF3 Lewis Structure
Lewis structure of Arsenic trifluoride (AsF3) contains three As-F bonds. Arsenic atom is located as the center atom in the molecule and each fluorine atom is located around arsenic atom. Each Fluorine atom has 3 lone pairs and also Arsenic atom has one lone pair. We will learn how to draw the lewis structure of AsF3 step by step in this tutorial.
AsF3 lewis structure
Figure of AsF3 lewis structure is given above and you can see how atoms are joint with other atoms. Also, there are no charges on atoms and AsF3 also does not have an overall charge.
Steps of drawing lewis structure of AsF3
There are several steps to draw the lewis structure of the AsF3. Each step is explained in detail in the remaining part of this tutorial.
- Find total number of electrons of the valance shells of Arsenic and Fluorine atoms
- Determine total electrons pairs as lone pairs and bonds
- Find center atom and basic sketch
- 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 AsF3
There are only two elements in AsF3 molecule; Arsenic and Fluorine. Arsenic is a group VA element and has only five electrons in its valence shell. Fluorine is a group VIIA element in the periodic table and contains 7 electrons in its last shell. Arsenic atom has five electrons in its last shell because it is a VA group element. Now we know how many electrons are includes in valence shells of atoms.
- valence electrons given by Arsenic atom = 5 * 1 = 5
- valence electrons given by fluorine atoms = 7 * 3 = 21
- Total valence electrons = 5 + 21 = 26
Total valence electrons pairs of AsF3
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, AsF3, total pairs of electrons are 13 (26/2) in their valence shells.
Selection of center atom and skeletal of AsF3
To be the center atom, ability of having greater valance and being most electropositive element in the molecule are important facts. These are not essential. But those two facts play a major role in selecting center atom of a molecule or ion in a covalent compound.
However, AsF3 is a simple molecule. Arsenic atom has the more chance to be the center atom than fluorine atom because Arsenic can show maximum valence of 5 while Fluorine's maximum valence is limited to 1.
And also, Arsenic is more electropositive element than Fluorine.
Determine lone pairs on atoms
After deciding the center atom and skeletal of AsF3 molecule, we mark lone pairs on atoms. Remember that, there are total of thirteen electron pairs to mark on atoms as bonds and lone pairs.
- There are already three bonds in the above drawn sketch. Now only ten (13-3) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms (on fluorine atoms, in this case). Therefore, mark electrons pairs on fluorine atoms; Each Fluorine atom will take three lone pairs. Now, nine electron pairs are marked on three Fluorine atoms.
- Now, one more electron pair is remaining to mark on atoms. Therefore, then mark that electrons pair on center Arsenic atom;
Mark charges on atoms and check the stability and minimize charges on atoms by converting lone pairs to bonds
There are no charges on atoms and we do not need to the step of reducing charges of atoms for obtaining most stable structure.
Questions
How AsF3 lewis structure is changed from NF3
Both AsF3 lewis structure and NF3 lewis structure have three sigma bonds and one lone pair around center atom. Therefore, their geometry and shapes are similar. But, bond lenghts and bond angles are different.