BeF2 Lewis structure

BeF₂ (beryllium fluoride) has one beryllium atom and two fluorine atoms.

In the BeF₂ Lewis structure, there are two single bonds around the beryllium atom, with two fluorine atoms attached to it, and on each fluorine atom, there are three lone pairs.

Alternative method: Lewis structure of BeF₂

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, beryllium lies in group 2, and fluorine lies in group 17.

Hence, beryllium has two valence electrons and fluorine has seven valence electrons.

Since BeF₂ has one beryllium atom and two fluorine atoms, so…

Valence electrons of one beryllium atom = 2 × 1 = 2
Valence electrons of two fluorine atoms = 7 × 2 = 14

And the total valence electrons = 2 + 14 = 16

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

• Second, find the total electron pairs

We have a total of 16 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 = 16 ÷ 2 = 8

• Third, determine the central atom

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

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

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

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 8 electron pairs. And two Be — F bonds are already marked. So we have to only mark the remaining six electron pairs as lone pairs on the sketch.

Also remember that both (beryllium and fluorine) are the period 2 elements, so they can not keep more than 8 electrons in their 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 beryllium, there is zero lone pair because all six electron pairs are over.

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 beryllium atom, formal charge = 2 – 0 – ½ (4) = 0

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

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

Final structure

The final structure of BeF₂ has a central beryllium atom connected to two fluorine atoms through single covalent bonds. In this configuration, the beryllium atom represents an exception to the octet rule as it reaches stability with only four valence electrons across its two bonding pairs. Each fluorine atom fulfills its octet by maintaining three lone pairs of its own alongside the single shared bond. This arrangement is the most stable because it results in formal charges of zero for all atoms involved, representing the most energetically favorable state for the molecule. As a result, this specific electronic distribution serves as the definitive and most accurate Lewis representation of beryllium fluoride.

Next: OH^– Lewis structure

External video

• BeF2 Lewis Structure – How to Draw the Lewis Structure for BeF2 – YouTube • Wayne Breslyn

External links

• https://topblogtenz.com/beryllium-fluoride-bef2-lewis-structure-molecular-electron-geometry-bond-angle-hybridization/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/BeF2-lewis-structure.html
• https://lambdageeks.com/bef2-lewis-structure/
• https://socratic.org/questions/how-can-i-draw-the-lewis-dot-structure-for-bef2