KrF4 Lewis structure

KrF₄ (krypton tetrafluoride) has one krypton atom and four fluorine atoms.

In the KrF₄ Lewis structure, there are four single bonds around the krypton atom, with four fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the krypton atom has two lone pairs.

Alternative method: Lewis structure of KrF₄

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, krypton lies in group 18, and fluorine lies in group 17.

Hence, krypton has eight valence electrons and fluorine has seven valence electrons.

Since KrF₄ has one krypton atom and four fluorine atoms, so…

Valence electrons of one krypton atom = 8 × 1 = 8
Valence electrons of four fluorine atoms = 7 × 4 = 28

And the total valence electrons = 8 + 28 = 36

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

• Second, find the total electron pairs

We have a total of 36 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 = 36 ÷ 2 = 18

• Third, determine the central atom

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

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

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

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 18 electron pairs. And four Kr — F bonds are already marked. So we have to only mark the remaining fourteen electron pairs as lone pairs on the sketch.

Also remember that krypton 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 krypton, there are two lone pairs.

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 krypton atom, formal charge = 8 – 4 – ½ (8) = 0

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

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

Final structure

The final structure of KrF₄ comprises a central krypton atom connected to four fluorine atoms via single covalent bonds. In this arrangement, the krypton atom utilizes an expanded octet to accommodate twelve electrons, which includes two lone pairs, while each fluorine atom fulfills its octet requirements with three lone pairs. This specific configuration is the most stable because it results in formal charges of zero for every atom, ensuring the molecule exists in its most energetically favorable state. Consequently, this square planar distribution of electrons represents the definitive and most accurate Lewis representation of krypton tetrafluoride.

Next: BrO₄^– Lewis structure

External video

• KrF4 Lewis Structure: How to Draw the Lewis Structure for KrF4 (Krypton Tetrafluoride) – YouTube • Wayne Breslyn

External links

• https://oneclass.com/homework-help/chemistry/7028130-krf4-lewis-structure.en.html