SeF5- Lewis Structure in 5 Steps (With Images)

So you have seen the above image by now, right?

Let me explain the above image in short.

SeF5- lewis structure has a Selenium atom (Se) at the center which is surrounded by five Fluorine atoms (F). There are 5 single bonds between the Selenium atom (Se) and each Fluorine atom (F). There are 3 lone pairs on all the Fluorine atoms (F) and 1 lone pair on the Selenium atom (Se). The Selenium atom has -1 formal charge.

If you haven’t understood anything from the above image of SeF5- ion lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of SeF5- ion.

So let’s move to the steps of drawing the lewis structure of SeF5- ion.

Steps of drawing SeF5 lewis structure

Step 1: Find the total valence electrons in SeF5- ion

In order to find the total valence electrons in a SeF5- ion, first of all you should know the valence electrons present in selenium atom as well as fluorine atom.
(Valence electrons are the electrons that are present in the outermost orbit of any atom.)

Here, I’ll tell you how you can easily find the valence electrons of selenium as well as fluorine using a periodic table.

Total valence electrons in SeF5- ion

→ Valence electrons given by selenium atom:

Selenium is a group 16 element on the periodic table. ^[1] Hence the valence electrons present in selenium is 6.

You can see the 6 valence electrons present in the selenium atom as shown in the above image.

→ Valence electrons given by fluorine atom:

Fluorine is group 17 element on the periodic table. ^[2] Hence the valence electron present in fluorine is 7.

You can see the 7 valence electrons present in the fluorine atom as shown in the above image.

Hence, 

Total valence electrons in SeF5- ion = valence electrons given by 1 selenium atom + valence electrons given by 5 fluorine atoms + 1 more electron is added due to 1 negative charge = 6 + 7(5) + 1 = 42.

Step 2: Select the central atom

For selecting the center atom, you have to remember that the atom which is less electronegative remains at the center.

Now here the given ion is SeF5- ion and it contains selenium atom (Se) and fluorine atoms (F).

You can see the electronegativity values of selenium atom (Se) and fluorine atom (F) in the above periodic table.

If we compare the electronegativity values of selenium (Se) and fluorine (F) then the selenium atom is less electronegative.

So here the selenium atom (Se) is the center atom and the fluorine atoms (F) are the outside atoms.

Step 3: Connect each atoms by putting an electron pair between them

Now in the SeF5 molecule, you have to put the electron pairs between the selenium atom (Se) and fluorine atoms (F).

This indicates that the selenium (Se) and fluorine (F) are chemically bonded with each other in a SeF5 molecule.

Step 4: Make the outer atoms stable. Place the remaining valence electrons pair on the central atom.

Now in this step, you have to check the stability of the outer atoms.

Here in the sketch of SeF5 molecule, you can see that the outer atoms are fluorine atoms.

These outer fluorine atoms are forming an octet and hence they are stable.

Also, in step 1 we have calculated the total number of valence electrons present in the SeF5- ion.

The SeF5- ion has a total 42 valence electrons and out of these, only 40 valence electrons are used in the above sketch.

So the number of electrons which are left = 42 – 40 = 2.

You have to put these 2 electrons on the central selenium atom in the above sketch of SeF5 molecule.

Now let’s proceed to the next step.

Step 5: Check the stability of lewis structure

Now you have come to the final step in which you have to check the stability of lewis structure of SeF5.

The stability of lewis structure can be checked by using a concept of formal charge.

In short, now you have to find the formal charge on selenium (Se) atom as well as fluorine (F) atoms present in the SeF5 molecule.

For calculating the formal charge, you have to use the following formula;

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

You can see the number of bonding electrons and nonbonding electrons for each atom of SeF5 molecule in the image given below.

For Selenium (Se) atom:
Valence electrons = 6 (because selenium is in group 16)
Bonding electrons = 10
Nonbonding electrons = 2

For Fluorine (F) atom:
Valence electrons = 7 (because fluorine is in group 17)
Bonding electrons = 2
Nonbonding electrons = 6

Formal charge	=	Valence electrons	–	(Bonding electrons)/2	–	Nonbonding electrons
Se	=	6	–	10/2	–	2	=	-1
F	=	7	–	2/2	–	6	=	0

From the above calculations of formal charge, you can see that the selenium (Se) atom has -1 charge and the fluorine (F) atoms has 0 charge.

So let’s keep these charges on the respective atoms in the SeF5 molecule.

This overall -1 charge on the SeF5 molecule is represented in the image given below.

In the above lewis dot structure of SeF5- ion, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of SeF5- ion.

I hope you have completely understood all the above steps.

For more practice and better understanding, you can try other lewis structures listed below.

Try (or at least See) these lewis structures for better understanding:

C2H3F Lewis Structure	NH2F Lewis Structure
SeI2 Lewis Structure	H2Te Lewis Structure
TeCl2 Lewis Structure	CH2I2 Lewis Structure