Lewis Structure of AsF6- (With 5 Simple Steps to Draw!)

Ready to learn how to draw the lewis structure of AsF6- ion?

Awesome!

Here, I have explained 5 simple steps to draw the lewis dot structure of AsF6- ion (along with images).

So, if you are ready to go with these 5 simple steps, then let’s dive right into it!

Lewis structure of AsF6- ion contains six single bonds between the Arsenic (As) atom and each Fluorine (F) atom. The Arsenic atom (As) is at the center and it is surrounded by 6 Fluorine atoms (F). All the six Fluorine atoms have 3 lone pairs. The Arsenic atom has -1 formal charge.

Let’s draw and understand this lewis dot structure step by step.

(Note: Take a pen and paper with you and try to draw this lewis structure along with me. I am sure you will definitely learn how to draw lewis structure of AsF6- ion).

5 Steps to Draw the Lewis Structure of AsF6- ion

Step #1: Calculate the total number of valence electrons

Here, the given ion is AsF6- ion. In order to draw the lewis structure of AsF6- ion, first of all you have to find the total number of valence electrons present in the AsF6- ion.
(Valence electrons are the number of electrons present in the outermost shell of an atom).

So, let’s calculate this first.

Calculation of valence electrons in AsF6- ion

• For Arsenic:

Arsenic is a group 15 element on the periodic table. ^[1]

Hence, the valence electrons present in arsenic is 5 (see below image).

• For Fluorine: 

Fluorine is a group 17 element on the periodic table. ^[2]

Hence, the valence electrons present in fluorine is 7 (see below image).

Hence in a AsF6- ion,

Valence electrons given by Arsenic (As) atom = 5
Valence electrons given by each Fluorine (F) atom = 7
Electron due to -1 charge, 1 more electron is added
So, total number of Valence electrons in AsF6- ion = 5 + 7(6) + 1 = 48

Step #2: Select the center atom

While selecting the atom, always put the least electronegative atom at the center. 

(Remember: Fluorine is the most electronegative element on the periodic table and the electronegativity decreases as we move right to left in the periodic table as well as top to bottom in the periodic table). ^[3]

Here in the AsF6 molecule, if we compare the arsenic atom (As) and fluorine atom (F), then the arsenic is less electronegative than fluorine.

So, arsenic should be placed in the center and the remaining 6 fluorine atoms will surround it.

Step #3: Put two electrons between the atoms to represent a chemical bond

Now in the above sketch of AsF6 molecule, put the two electrons (i.e electron pair) between each arsenic atom and fluorine atom to represent a chemical bond between them.

These pairs of electrons present between the Arsenic (As) and Fluorine (F) atoms form a chemical bond, which bonds the arsenic and fluorine atoms with each other in a AsF6 molecule.

Step #4: Complete the octet (or duplet) on outside atoms. If the valence electrons are left, then put the valence electrons pair on the central atom

Don’t worry, I’ll explain!

In the Lewis structure of AsF6- ion, the outer atoms are fluorine atoms.

So now, you have to complete the octet on these fluorine atoms (because fluorine requires 8 electrons to have a complete outer shell).

Now, you can see in the above image that all the fluorine atoms form an octet.

Also, all the 48 valence electrons of AsF6- ion (as calculated in step #1) are used in the above structure. So there are no remaining electron pairs.

Hence there is no change in the above sketch.

Let’s move to the next step.

Step #5: Final step – Check the stability of lewis structure by calculating the formal charge on each atom

Now, you have come to the final step and here you have to check the formal charge on arsenic atom (As) as well as each fluorine atom (F).

For that, you need to remember the formula of formal charge;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

• For Arsenic:
  Valence electrons = 5 (as it is in group 15)
  Nonbonding electrons = 0
  Bonding electrons = 12
• For Fluorine:
  Valence electron = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 2

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
As	=	5	–	0	–	12/2	=	-1
F	=	7	–	6	–	2/2	=	0

Let’s keep these charges on the atoms in the above lewis structure of AsF6- ion.

As you can see in the above sketch, there is one -ve charge on the arsenic atom, which indicates the -1 formal charge on the AsF6- molecule.

Hence, the above lewis structure of AsF6- ion is the stable lewis structure.

Each electron pair (:) in the lewis dot structure of AsF6- ion represents the single bond ( | ). So the above lewis dot structure of AsF6- ion can also be represented as shown below.

Related lewis structures for your practice:
Lewis Structure of SCl6
Lewis Structure of SeCl2
Lewis Structure of C2F4
Lewis Structure of IBr3
Lewis Structure of HBrO 

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