Bef2 Lewis Structure,Characteristics:13 Must To Know Facts


We are going discuss about beryllium fluoride,BeF2 lewis structure, hybridisation, valence electrons and other detailed information in this article.

Beryllium fluoride,BeF2 is an inorganic compound which looks like a white solid substance. Its structure is similiar to quartz and has some special optical properties.

How to draw BeF2 Lewis structures ?

 The bond formation between two or more atoms can be easily understand by illustrating its Lewis structure. While sketching the Lewis structure of an atom only its valence electrons are considered. The valence electrons and bonds between the atoms are indicated by some dots and lines respectively. Structures depicted  by this way are called Lewis dot structure.

We can draw Lewis dot structures for both covalently bonded and ionic bonded compounds. Beryllium fluoride is an inorganic compound having one  beryllium and two fluorine atom. Beryllium is a second group alkaline earth metal and fluorine is from halogen family. We have to keep certain rules for drawing the Lewis structure of any compound. They are

  • For drawing the Lewis structure first we need to calculate the entire number of valence electrons present in the given compound. It is done by adding the electrons present in the outer shell of each atom. In BeF2, Be has 2 and fluorine has 7 outer electrons. So in total, there is 2+7×2 = 16 electrons.
  • In BeF2, there is one beryllium atom having two valence electrons and two fluorine atoms with seven valence electrons.
  •  Beryllium atom shares two of its valence electrons to the two fluorine atom and hence they form two Be – F single bonds.

BeF2 Resonance

The delocalisation of electrons linked with an atom is the cause of resonance. Due to this process a molecule or compound can have more than one structures. Such structures are called its resonating structure or resonance structure. This process can be seen in double bonded compounds and compounds with lone pair of electrons.

When we draw this structure the molecular formula of the compound shouldn’t change. Since there is no double bond present in between beryllium and fluorine there is no resonance structure for beryllium fluoride.

BeF2  Shape

Beryllium fluoride is made by sharing of electrons between one beryllium atom and two fluorine atoms. Its shape is linear. A linear molecule is a molecule where the atoms are arranged along a straight line. Here the two fluorine atoms are arranged on both the sides of beryllium through a straight line pattern.

Shape of BeF2

BeF2 Formal charge

The charge allotted to an atom as a result of its bond formation with another atom is called formal charge. The equation for finding the formal charge of an atom is 

Formal charge of an atom = ( Valence electrons – No. of lone pairs – No. of bonds formed)

Formal charge of Beryllium in BeF2 = 2 – 0- 2

                                                        = 0

Formal charge of fluorine in BeF2 = 7 – 6- 1

                                                            = 0

So the formal charge of both the beryllium and fluorine in BeF2 is 0.

BeF2 Bond angle

When atoms combines to form stable compound, an angle is formed in between the bonds. The angle formed as result of bond formation between two or more atoms is called bond angle.

Beryllium fluoride is a linear shaped molecule. In a linear shaped molecule the atoms will be arranged in straight line. So the bond angle between the beryllium and fluorine atoms is 1800.

Angle of BeF2

BeF2 Octet rule

Octet rule states that, whenever atoms undergo combination to form stable compounds their outermost shell should be filled with eight electrons. In the case of covalent compound they share their electrons to obey octet rule. In ionic compound they will either lose or gain electrons to make their octet filled.

In the case of beryllium fluoride, beryllium has two electrons and fluorine has seven a electrons in its valence shell. When beryllium shares its two electrons with two fluorine atoms then fluorine got satisfied with octet rule. After bond formation between Be and F the fluorine atom has eight electrons in its outer shell. But beryllium contains only four electrons. Molecules like hydrogen, helium, lithium, beryllium don’t need eight electrons in their valence shell to get stabilised. So beryllium in BeF2 is an exception to octet rule.

Valence electrons in BeF2

BeF2 Lone pair of electrons

Some of the electrons present in the valence shell doesn’t participate in bond formation and they will stay with the atom. Those electrons are termed as lone pair of electrons or non bonding electrons.

In beryllium there is no lone pair of electron.

The lone pair of electrons present  in Fluorine atom is 3.

BeF2 Valence electrons

The electrons connected with an atom which can only participates in bond construction is known as valence electrons.

In Be there is two valence electrons and Fluorine there is seven valence electrons. So in total there is 2+7×2 = 16 valence electrons in BeF2.

BeF2 Hybridisation

 Sometimes atomic orbitals with various energies combines to form new orbitals with same energy and shape. This is called hybridisation. Hybrid orbitals are the new orbitals formed by this way. The number of orbitals formed will be equal to the number of orbitals undergo hybridisation.

The electronic configuration of  Be in its ground state is 1s2 2s2. In the next step one electron in 2s orbital will be excited to the 2px orbital. Then its electronic arrangement changes to 1s2 2s1 2p1. After this the 2s and 2px orbital overlap together to form two sp orbitals with same energy. The angle between these two orbitals is 1800 and they are oriented in opposite direction.

Then two fluorine atom shares one electron from its 2pz  orbital to beryllium. This results the formation of  BeF2 bond. This results the formation two sigma or single bond  between beryllium and fluorine. So the hybridisation in beryllium fluoride is sp hybridisation.

The orbitals formed as result of Hybridisation has 50% s character and 50% p character. This can be also termed as diagonal hybridisation.

Hybridisation in BeF2

BeF2 Solubility

The capability of the substance to get dissolved in a solvent is called solubility. The frequently used solvents are water, ethanol, acetone, chloroform, ether, CCl4, benzene. Beryllium fluoride is found to be miscible in water and are sparingly soluble in ethanol.

 Is BeF2  Ionic or not ?

 A positive charged and negative charged ion attracts together to form ionic bond. These positive and negative ions are cation and anion respectively. A covalent bond is formed by the common distribution of electrons between the atoms with same or different electronegativity value.

Beryllium fluoride is formed by the sharing of atoms between beryllium and fluorine. So BeF2 is a covalent compound with linear shape.

Is BeF2 Polar or not ?

BeF2 is a molecule which exhibits Non polar character. Because the two Be – F bonds are symmetrical to each other their dipole moment got cancelled each other. So the net dipole moment is 0. Therefore Beryllium fluoride is Non polar molecule.

Is BeF2 Acidic or Basic ?

BeF2 is acidic in nature. Lewis acid is an acid which can accepts electrons from other atoms. Beryllium fluoride can be a good lewis acid because beryllium can accepts more electrons.

Summary

Beryllium fluoride is an inorganic compound with formula BeF2.It is a white solid which is used as precursor for the synthesis of beryllium. This article explains the lewis structure of  beryllium fluoride and its other properties like its hybridisation, solubility, acidic behaviour and its polar nature.

Aparna Dev

Hi... I am Aparna Dev, a chemistry postgraduate with a good understanding of chemistry concepts. I am working in Kerala Minerals and Metals Limited Kollam with experience in the development of electrocatalysts as a part of post graduate thesis. Let's connect through LinkedIn-https://www.linkedin.com/in/aparna-dev-76a8751b9

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