ICL2- lewis structure: Drawings, Hybridization, Shape, Charges, Pairs

In this article, “icl2- lewis structure”, different facts like hybridization, shape, formal charge calculation, stability of ICl2 with some detailed explanations are discussed thoroughly.

ICl2 is an interhalogen compound in which iodine is connected with two chlorine atoms by two covalent bonds. In it, iodine is sp3d hybridized with a linear structure. It has two bond pair and three lone pair and angle between two I-Cl is 1800. Due to its linear shape, it is a nonpolar molecule.

Let’s focus on the following relevant topics on ICl2.

How to draw ICl2 lewis structure?

Lewis structure is one of the structural representation of any molecule in which nonbonding electrons are shown around each of the atom and the bonds between the atoms.

The process of drawing the lewis structure is described below-

  1. Finding out the valance electrons: The first step of lewis structure drawing is to determine the valance shell electron. In ICl2, both the halogen atom, iodine and chlorine have seven electrons in their respective outer most shell. Iodine is in -1 oxidation state. Thus, it has eight electrons in its valance shell.
  2. Determine the bonding electrons: ICl2 has total two covalent bonds in it. Thus, (2×2=4) electrons are involved in two covalent bond formation
  3. Determine the nonbonding electrons: In ICl2, total three lone pairs and two bond pairs are present between iodine and two chlorine atoms. Thus, iodine has (3×2=6) nonbonding electrons and each of the chlorine atom has six electrons remain as nonbonding.

Total nonbonding electrons in ICl2 is { 6 + (6×2) } = 18

ICl2 Lewis Structure Shape

The factor “hybridization” plays the most significant role in structure determining. Molecular shape is changed with the change of central atom hybridization (shown below).

Hybridization of central atom  Structure
sp Linear
sp2 Trigonal planar
sp3 Tetrahedral
sp3d Trigonal bipyramidal
sp3d2 Octahedral

 Not only hybridization, some times lone pair bond pair repulsion also determines the structure of any molecule. Three types of repulsion are responsible in the structure determination-

  • Lone pair- lone pair repulsion
  • Lone pair-bond pair repulsion
  • Bond pair-bond pair repulsion

The increasing order of the above repulsion is-

Lone pair -lone pair repulsion > Lone pair – bond pair repulsion > Bond pair- bond pair repulsion.

In ICl2, iodine has three lone pairs. These lone pairs face repulsion from each other and from the bonding electrons also. Iodine is sp3d hybridized in ICl2. Thus, its actual geometrical structure should be trigonal bipyramidal or TBP. But due to presence of these lone pair, the actual structure is distorted and it becomes linear.

In TBP, there is two types of position for the substituent atoms. One is axial position and another one is equatorial position. Three lone pairs are placed in the three equatorial position and two Cl atoms are placed in the two axial position of TBP structure according to the VSEPR theory due to minimize the lone pair bond pair repulsion. Placing the two Cl atoms in the axial position make the molecule, ICl2 a linear shaped and bond angle between two I-Cl bonds becomes 1800.

ICl2 shape
Shape of ICl2

ICl2 Lewis Structure Formal Charge

Formal charge of any molecule is calculated to check if the electrons in all the chemical bonds are shared equally to all over the atoms or not. Calculation of formal charge also helps to find out the most stable lewis structure of any molecule.

  • Formal charge = Total number of valance electrons – number of electrons remain as nonbonded – (number of electrons involved in bond formation/2)
  • Formal charge of iodine = 7 – 6 – (4/2) = -1
  • Formal charge of each of the chlorine atom = 7 – 6 – (2/2) = 0

Iodine is in -1 oxidation state in ICl3. Thus, it contains eight electrons in its valance shell and each of the two chlorine atoms has seven electrons in their valance shell. Iodine is connected by two covalent bonds with two chlorine atoms. So, 4 electrons (2×2) and 2 electrons (2×1) are involved in bond formation for iodine and chlorine atom respectively.

ICl2 Lewis Structure Angle

Bond angle is nothing but the angle between two covalent bonds. Hybridization also helps to determine the bond angle in a molecule. Hybridization is responsible to change the bond angle in any molecule.

 Three lone pair and two lone pair are present in ICl2 molecule. Due to presence of two lone pair of iodine, two chlorine atoms are placed in the two axial position of TBP structure. The three atom, iodine and two chlorine are oriented in a straight line keeping the three lone pair in three equatorial position.

Due to having linear structure the angle between two I-Cl bond is 1800 and the angle between one lone pair with a bond pair is 900 (right angle).

ICl2 Lewis Structure Octet Rule

Octet rule is one of the most significant rule in chemistry as it says that any atom should have eight electrons in its valance shell to match the electron configuration with its nearest noble gas. This special electron configuration gives any atom an extra stability.

Octet rule is not satisfied in ICl2 molecule. Three lone pairs and two bond pairs are involved in this molecular species. Thus, it has ten electrons in its valance shell (including nonbonding and bonding electrons). This number of electrons do not resemble with the nearest noble gas Xenon or Xe (5s2 5p6).

But each of the chlorine atom  obeys octet rule in ICl2 molecule. The chlorine atom has three pair of nonbonding electrons and one of the valance electron of it is involved in covalent bond formation with iodine atom. So, it gains total eight electrons in its valance shell that matches with the electron configuration of nearest noble gas Argon or Ar (3s2 3p6).

ICl2 Lewis Structure Lone Pairs

Lone pairs or nonbonding electrons are two similar words. Both of these words are carrying same meaning in chemistry. Lone pairs are those valance electrons who are not responsible for bond formation. Basically, nonbonding electrons or lone pairs are those valance electrons left after bond formation.

  • Nonbonded electron = Total number of valance electron – number of bonded electrons.
  • Nonbonding electrons on Iodine (I) = 8 – 2 = 6 or 3 lone pair
  • Nonbonding electrons on each of the chlorine atoms (Cl) = 7 – 1 = 6 or three lone pairs.

Being halogen atom, both the iodine and chlorine have same number of electrons in their valance shell (ns2 np5). But iodine is negatively charged in ICl2 and I has eight electrons in its valance shell.

Thus, total number of nonbonding electrons in ICl2 is { 6 + (2×6)} = 18 or 9 lone pairs.

ICl2 Valence Electrons

Valance electrons are those who are revolving around the nucleus from the outer most shell of any atom. Atoms take part in any reaction just because of these valance electrons due to the lesser attraction of nucleus on them. Inner shell electrons are very strongly attracted by the nucleus. Thus, they can’t participate in any reaction.

As iodine and halogen are two halogen compounds, they have same electrons in their valance shell. Iodine and chlorine have electron configuration in their valance shell are 5s2 5p5 and 3s2 3p5. Due to achieving -1 oxidation state, I has eight electrons in its outer most shell.

Thus, total number of valance electrons in ICl2 are {8 + (7×2)} = 22.

ICl2 Hybridization

Hybridization is introduced in chemistry as the mixing of two atomic orbitals having similar energies, size and symmetry. There are five basic types of hybridization. Thy are-

  1.  Planar (sp)
  2. Trigonal Planar (sp2)
  3. Tetrahedral (sp3)
  4. Trigonal bipyramidal (sp3d2)
  5. Octahedral (sp3d2)

In ICl2, central atom, iodine is sp3d hybridized having three lone pair and two bond pair. One s orbital, three p orbital and one d orbital of iodine are involved in this sp3d hybridization. Each of the chlorine atom shares their only one valance electron with iodine in this hybridization.

ICl2 Hybridization
Hybridization of ICl2

Sp3d hybridization directs a molecule to be TBP structured but due to presence of three lone pair, its actual geometrical structure is violated and becomes linear.

Is ICL2 ionic or covalent?

The main difference between a covalent and ionic compound is that electrons are shared in covalent compound but they are completely donated in ionic compound from electropositive element to electronegative element.

In ICl2, electrons are shared between iodine and two chlorine atoms. Not only that it has one of the most important features of covalent compound that iodine and chlorine both are nonmetal compounds. The electronegativity difference between iodine and chlorine is also not high (The electronegativity of iodine and chlorine are 2.66 and 3.16 respectively). But for being an ionic compound this difference must be high and the participating atoms must be metal and nonmetal combination.

Thus, ICl2 is a covalent compound.

Is ICL2 stable?

ICl2 is moderately stable compound. It is less stable than any di halogen compound like I2 or Cl2 due to comparatively poor overlap of atomic orbitals.

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