Lewis structure of SeF2

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The Lewis structure of SeF₂ contains two single bonds, with selenium in the center, and two fluorines on either side. There are three lone pairs on each fluorine atom, and two lone pairs on the selenium atom.

Steps

By using the following steps, you can easily draw the Lewis structure of SeF₂.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… selenium is a group 16 element and fluorine is a group 17 element. Hence, selenium has six valence electrons and fluorine has seven valence electrons.

Now SeF₂ has one selenium atom and two fluorine atoms.

So the total number of valence electrons = valence electrons of selenium atom + (valence electrons of fluorine atom × 2)

Therefore, the total number of valence electrons = 6 + 14 = 20

• Now decide the central atom

The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for selenium and fluorine as follows:

Electronegativity value of selenium = 2.55
Electronegativity value of fluorine = 3.98

Obviously, selenium is less electronegative than fluorine. Hence, assume that selenium is the central atom.

So now, put selenium in the center and fluorines on either side. And draw the rough skeleton structure for the Lewis structure of SeF₂ something like this:

Also read: How to draw Lewis structure of NO₄^3- (5 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since selenium is surrounded by two fluorines, use four electrons to show two chemical bonds as follows:

Also read: How to draw SF₃⁺ Lewis structure (4 steps)

#3 Mark lone pairs

As calculated earlier, we have a total of 20 valence electrons. And in the above structure, we have already used four valence electrons. Hence, sixteen valence electrons are remaining.

Two valence electrons represent one lone pair. So sixteen valence electrons = eight lone pairs.

Note that selenium is a period 4 element, so it can keep more than 8 electrons in its last shell. And fluorine is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are fluorines, so each fluorine will get three lone pairs. And the central atom (selenium) will get two lone pairs.

So the Lewis structure of SeF₂ looks something like this:

In the above structure, you can see that the octet is completed on the central atom (selenium), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of C₂Cl₂ (5 steps)

#4 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

Collect the data from the above structure and then, write it down below as follows:

• For selenium atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

• For each fluorine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of SeF₂ looks something like this:

In the above structure, you can see that the formal charges of both (selenium and fluorine) are zero. Therefore, this is the stable Lewis structure of SeF₂.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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Related

• Lewis structure of NO₄^3-
• SF₃⁺ Lewis structure
• Lewis structure of C₂Cl₂
• Lewis structure of CH₃CH₂NH₂
• Lewis structure of NF₂^–

External video

• How to Draw the Lewis Dot Structure for SeF2: Selenium difluoride – Wayne Breslyn

External links

• SeF2 Lewis Structure in 6 Steps (With Images) – Pediabay
• Draw and explain the Lewis structure of SeF2 – Homework.Study.com
• Draw a Lewis structure for SeF2, and then write the number of bonded pairs and lone pairs of electrons are present around the central atom – Chegg
• What is the molecular structure for SeF2? – Answers
• Draw the Lewis structure for SeF2 (selenium difluoride) – Numerade
• Draw a Lewis structure for SeF2, and then write the number of bonded pairs and lone pairs of electrons are present around the central atom – OneClass
• SeF2 (Selenium Difluoride) Oxidation Number – ChemicalAid
• Selenium difluoride | F2Se | CID 139663 – National Institutes of Health (.gov)