ZnCl2 Structure & Characteristics (13 Important Facts)

ZnCl₂ or zinc Chloride is halogenated salt of Zinc having a molecular weight of 136.286 g/mol. Let us learn about ZnCl₂ in detail.

ZnCl₂ is a borderline element molecule, it is a d¹⁰ system. It is a halogenated salt of the d-block element. The oxidation state of the Zn is +2 and the stable valency of Zn two is maintained here. The molecule has not any crystal field stabilization as the d orbital of Zn is filled with electrons.

ZnCl₂ is diamagnetic in nature because the d orbitals filled with 10 electrons and there are no unpaired electrons are present. Now we will discuss hybridization, lewis structure, polarity, and many more of the ZnCl₂ with proper explanation in the following section of this article.

1.     How to draw the ZnCl₂ structure?

The lewis structure of ZnCl₂ can give us a clear idea of the molecular property. Let us discuss how to draw structure of the ZnCl₂ in a few steps.

Counting the valence electrons

While drawing the lewis structure of any molecule first of all we should count the total valence electrons of that molecule by counting the valence electrons of the substituent atoms. The total valence electrons for the ZnCl₂ are 16 where two are from Zn and 14 are from two Cl sites, so we add them together.

Choosing the central atom

The 2^nd  step for lewis structure drawing is selecting the central atom for a molecule among all the substituent atoms. Zn is selected as the central atom here based on the electropositivity and size of the atom. two Cl atoms are present at the terminal atoms in this molecule.

Satisfying the octet

After the bond formation, each atom of a molecule should follow the octet rule by completing its valence orbital with a suitable number of electrons. Zn is a d block element so it needs 10 electrons in the valence orbital and Cl needs 8 electrons to complete the octet. They share electrons while they form a bond.

Satisfying the valency

During the octet formation, each atom should maintain its stable valency based on its oxidation state. Here Zn is +2 oxidation state, so the stable valency for Zn is here 2 and it is maintained because it forms two bonds with two Cl atoms, and each Cl atom is also satisfied by their mono valency.

Assign the lone pairs

The excess nonbonded electrons present in the valence orbital of a particular atom exist as lone pairs. In the ZnCl₂ all the valence electrons of the Zn are used in the bond formation so it lacks lone pairs but each Cl has three pairs of lone pairs because only one electron is being used in bond formation.

2.     ZnCl₂ structure valence electrons

The valence electrons are counted as those electrons present in the outermost shell of every individual atom. now we count the total valence electrons for the ZnCl₂.

The total number of valence electrons for the ZnCl₂ molecule is 16. This number is the summation of the valence electrons of the Zn and two Cl atoms. Valence electrons for the molecule are the total number of valence electrons shared by the individual atoms.

• The valence electrons for the Zn are 2 (as the d orbital is fully completed and two electrons in the 4s orbital)
• The valence electrons for each Cl atom are 7 (belong to halogen or group 17^th element)
• So, the total number of valence electrons for the ZnCl₂ molecule is 2+7+7 = 16

3.     ZnCl₂ structure lone pairs

The remaining valence electrons in the outermost orbital are considered lone pairs of the atom. Let us count the lone pairs present over the ZnCl₂.

ZnCl₂ contains a total number of 12 lone pairs which belong to Cl atoms only not the Zn. Each Cl has six lone pairs of electrons or three pairs because it has seven valence electrons, and after maintaining its mono valency remaining six electrons exist as lone pairs, but Zn has not any.

• The formula is being used to count the lone pairs = electrons present in the valence shell – electrons involved in the bond formation
• The lone pairs present over the Zn atom are, 2-2 =0
• The lone pairs present over each Cl center are, 7-1 = 6
• So, the total lone pairs over the ZnCl₂ molecule are, 6*2 = 12 lone pairs electrons or 6 pairs

4.     ZnCl₂ structure shape

The molecular shape is a particular shape adopted by the molecule after the bond formation among constituent atoms. Let us predict the shape of the ZnCl₂.

ZnCl₂ adopts the linear geometry around the central Zn atom and both Cl atoms are present in the same plane of the molecule, which can be considered in the following table.

Transition metal element having filled d orbital or d¹⁰ atom always form linear molecule because it has not any crystal field stabilization, so due to avoiding the steric crowding, it forms linear geometry. For the linear geometry, its hybridization should be sp for the central atom.

5.     ZnCl₂ structure angle

The bond angle is the angle made by the constituent atom with the central atom for proper orientation. Let us calculate the bond angle for the ZnCl₂ molecule.

The bond angle for the linear molecule is 180⁰, being a linear molecule the bond angle for the ZnCl₂ is the same. This value of angle can be predicted by the VSEPR (Valence Shell Electrons Pair repulsion) theory, even from the hybridization value bond angle will be calculated.

• The bond angle formula according to Bent’s rule is COSθ = s/(s-1).
• The central atom Zn is sp hybridized, so the s character here is 1/2^th
• So, the bond angle is, COSθ = {(1/2)} / {(1/2)-1} =-(1)
• Θ = COS^-1(-1) = 180⁰
• So, the bond angle for the ZnCl₂ is 180⁰ is being calculated.

6.     ZnCl₂ structure hybridization

Atomic orbitals of different energy undergo hybridization to form equivalent energy-containing hybrid orbitals. Now we explore the hybridization of the ZnCl₂.

The central Zn is sp hybridized in the ZnCl₂ molecule as its d orbitals are filled, which can be confirmed by the following table.

• We can calculate the hybridization by using the formula, H = 0.5(V+M-C+A),
• So, the hybridization of central Zn is, ½(2+2+0+0) = 2 (sp)
• One s orbital and one p orbital of Zn is involved in the hybridization.
• The lone pairs of Cl are not involved in the hybridization.

_7.          Properties of ZnCl₂

The physical properties are those which cannot be changed during the chemical reaction of the molecule. Let us know the physical properties of ZnCl₂.

Those are the basic physical characteristics of ZnCl₂, apart from these, it has many chemical properties when it reacts with proper reagents.

8.     ZnCl₂ solubility

The solubility of ZnCl₂ is various solvents observed but in water, it has greater solubility than other solvents. Let us discuss the solubility of ZnCl₂.

ZnCl₂ has a greater solubility in water because it has a partial ionic character and due to the size mismatching Zn and Cl bonds easily break in water solution and gets dissolved in it. The Chloride ions also form H-bonding with water to increase its solubility to another aprotic solvent.

Apart from water, ZnCl₂ can be soluble in the following solvents

• Ethanol
• Acetone
• Glycerol

9.     Is ZnCl₂ solid or liquid?

The physical state or nature of a molecule depends on the constituents present in to it and also temperature. Let us see whether ZnCl₂ is solid or liquid.

ZnCl₂ is solid in nature because it is made by strong ionic force in between the atoms. The van der Waal’s force of attraction is very high for this molecule, it exists as a solid white powder. The lattice structure of the crystal is a zinc blend, so it has a strong internal force and exists as a solid at room temperature.

It is a crystalline solid molecule and the hydrated part of the molecule exists in the lattice structure.

10. Is ZnCl₂ polar or nonpolar?

If there is a resultant dipole moment is present then the molecule is said to be polar otherwise not. Let us check whether ZnCl₂ is polar or nonpolar.

ZnCl₂ is a non-polar molecule and the main reason behind its non-polarity is the shape of the molecule. Due to its linear shape, the dipole-moment from Zn to both Cl are the same in magnitude but opposite in direction, so they cancel out each other, and there is zero resultant dipole-moment for the molecule.

11. Is ZnCl₂ acid or base or salt?

A molecule is an acid or base depending on the value of pH, again it is formed by the reaction of acid and base then it will be salt. Let us see the nature of ZnCl₂.

ZnCl₂ is a salt because it formed by the cation and anion other than H⁺ and OH^– and also there is ionic interaction is present in the molecule. Also, it is prepared by the reaction of zinc hydroxide and hydrochloric acid, so it is made by the reaction of acid and base, so it is a salt.

It is a good lewis acid because it can accept electrons in its vacant orbital from electron rich centre.

12. Is ZnCl₂ electrolyte?

If a substance carries electricity through an aqueous solution by dissolving in it, is called an electrolyte. Let us see whether ZnCl₂ is an electrolyte or not.

ZnCl₂ is an electrolyte because it gets dissociated with ions in the aqueous solution by full hydrolysis. After ionization it formed Zn²⁺ and 2Cl^– ions, those ions are highly charged particles, cation contains +2 charge, and chloride ions are highly electronegative, so they can carry electricity through the solution very quickly.

On the other hand, we can say that as ZnCl₂ is salt so it can carry electricity and behaves as an electrolyte.

13. Is ZnCl₂ ionic or covalent?

Ionic or covalent nature is depending on the theory of polarizability of Fajan’s rule, each molecule has both characteristics. Let us see whether ZnCl₂ is ionic or covalent.

ZnCl₂ is an ionic molecule because there is strong ionic interaction occurring between highly electropositive Zn²⁺ and highly electronegative Cl^– atoms. The size of Zn²⁺ is very small s it contains 10 d electrons, so it has a higher ionic potential and it can easily polarize the Cl^– ions having polarizability.

But it has some covalent character because it is formed via hybridization also.

14. Is ZnCl₂ an inorganic compound?

Apart from all the hydrocarbons, all the molecules consisting of different atoms are known as inorganic compounds. Let us check if ZnCl₂ is an inorganic compound or not.

ZnCl₂ is an inorganic compound because it is made by the Zn and Cl which are different from hydrocarbon. C and H-containing molecule is referred to as hydrocarbon but here the molecule is the absence of those atoms, so it is a pure inorganic compound and it has various inorganic characteristics.

Conclusion

ZnCl₂ is an inorganic neutral salt. It is a compound of d block element and has a filled d orbital by electrons, so there is no charge transfer occurring due to d-d- transition. That’s why it exists white in color. It is also a good lewis acid because it can accept electrons in the vacant orbital of Zn and is used in many organic reactions.

Biswarup Chandra Dey

Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.