In this post, we will be drawing the Lewis structure, and determining the geometry and hybridization of AsF₅.

 

AsF₅ Lewis Structure

The first thing we need to do when drawing a Lewis structure is determine the total number of valence electrons in the molecule. Remember, valence electrons are those in the outermost principal energy level. For example: Na – 1s²2s²2p⁶3s¹, Cl – 1s²2s²2p⁶3s²3p⁵
The number of valence electrons, for main group elements, corresponds to their group number in the periodic table:

 

 

For d block elements, the outermost d electrons are also counted as valence electrons (ns + (n-1)d). For example, iron has eight valence electrons: Fe – 1s²2s²2p⁶3s²3p⁶4s²3d⁶.

Arsenic is the central atom:

 

Arsenic is in group 5, so it has five valence electrons, while chlorine, being in group 7, has seven valence electrons. Therefore, there are, in total, 5×7 + 5 = 40 electrons, out of which, 10 are used to make 5 covalent bonds. All the remaining 30 are divided between the five fluorine atoms, each taking 6 electrons as 3 lone pairs:

 

 

There are 5 atoms and no lone pairs on the central atom, therefore, both geometries are trigonal bipyramidal:

 

AsF₅ Hybridization

The steric number of arsenic is 5 – five atoms, with no lone pairs, and therefore, the hybridization is sp³d. 

 

Check this 99-question multiple-choice quiz on Geometry and Hybridization:

Check Also

• Lewis Dot Symbols
• Valence Electrons
• The VSEPR Model
• Lewis Structures Practice Problems
• VSEPR Theory Practice Problems
• Hybridization of Atomic Orbitals
• sp, sp², sp³, sp³d, and sp³d² Hybridization Practice Problems