SeF4 Lewis structure

SeF₄ (selenium tetrafluoride) has one selenium atom and four fluorine atoms.

In the SeF₄ Lewis structure, there are four single bonds around the selenium atom, with four fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the selenium atom has one lone pair.

Alternative method: Lewis structure of SeF₄

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, selenium lies in group 16, and fluorine lies in group 17.

Hence, selenium has six valence electrons and fluorine has seven valence electrons.

Since SeF₄ has one selenium atom and four fluorine atoms, so…

Valence electrons of one selenium atom = 6 × 1 = 6
Valence electrons of four fluorine atoms = 7 × 4 = 28

And the total valence electrons = 6 + 28 = 34

Learn how to find: Selenium valence electrons and Fluorine valence electrons

• Second, find the total electron pairs

We have a total of 34 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 34 ÷ 2 = 17

• Third, determine the central atom

We have to place the least electronegative atom at the center.

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

Therefore, place selenium in the center and fluorines on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 17 electron pairs. And four Se — F bonds are already marked. So we have to only mark the remaining thirteen electron pairs as lone pairs on the sketch.

Also remember 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.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are fluorines.

So for each fluorine, there are three lone pairs, and for selenium, there is one lone pair.

Mark the lone pairs on the sketch as follows:

Formal charge

Use the following formula to calculate the formal charges on atoms:

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

For selenium atom, formal charge = 6 – 2 – ½ (8) = 0

For each fluorine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, both selenium and fluorine atoms do not have charges, so no need to mark the charges.

Final structure

The final structure of SeF₄ comprises a central selenium atom linked to four fluorine atoms through single covalent bonds. In this configuration, the selenium atom utilizes an expanded valence shell to accommodate ten electrons, which include four bonding pairs and one lone pair. Within this layout, each of the four fluorine atoms satisfies the octet rule by retaining three lone pairs alongside its single shared bond. This arrangement represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of selenium tetrafluoride.

Next: CO₃^2- Lewis structure

External video

• SeF4 Lewis Structure – How to Draw the Lewis Structure for SeF4 – YouTube • Wayne Breslyn

External links

• https://techiescientist.com/sef4-lewis-structure/
• https://topblogtenz.com/sef4-lewis-structure-molecular-geometry-polarity/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/SeF4-lewis-structure.html
• https://socratic.org/questions/5326455f02bf3466abc1e4f7