Ci4 lewis structure,Characteristics:13 Facts You Should Know

In this article, we will discuss the CI4 lewis structure, shape, formal charge, hybridization, and other 13 important facts of CI4.

CI4 or carbon tetraiodide is a tetrahalomethane in which carbon is attached to four iodine atoms via covalent bonds and is sp3 hybridized. It is tetrahedral in shape with bond angles of 109.5. It has a bright red color and decomposes readily to give tetraiodoethylene C2I4.

Its molecular weight is 519.63g. It is thermally and photochemically unstable. Its bond length is 2.12 Å.

How to draw Ci4 lewis structure?

Lewis structure is a visual representation of the arrangement of electrons in a molecule. We will follow the  mentioned steps to draw the CI4 lewis structure.

Step 1: Identify the central atom

In the CI4 lewis structure, carbon is the central atom as it is the least electronegative atom and  the only atom which can form more than one bond. We will place carbon in the center and iodine atoms around it.

Step 2: Count the total number of valence electrons on each atom

Carbon belongs to group 14, it has four valence electrons. Iodine belongs to group 17, it has seven valence electrons. Four iodine atoms exist in the CI4 lewis structure, each with seven valence electrons. The total number of valence electrons will be 4+7*4=32.

Step 3: Satisfy the octet on each atom

We will start by drawing a single bond between carbon and iodine atoms and place the remaining valence electrons as lone pairs on iodine to satisfy the octet of every atom.The CI4 lewis structure is shown below:

Ci4 lewis structure octet rule

The basis of chemical bonding is stability. Atoms try to achieve stability in several ways, one being completing their octet.

Atoms try to gain stability by gaining eight electrons(octet) in their valence shell. Not all atoms obey this rule; many are stable without having eight electrons in the valence shell(hydrogen, helium, lithium, phosphorous, sulfur, etc.).In the CI4 lewis structure, carbon has four electrons in its valence shell(2s22p2).

It needs four more electrons to complete its valence shell. Carbon completes its octet by forming four covalent bonds and sharing its valence electrons with iodine atoms. Iodine has seven electrons in its valence shell(5s25p5); it needs one electron to complete its octet. It shares an electron with carbon(and vice-versa) and forms a covalent bond.

Ci4 lewis structure formal charge

A formal charge helps assign a charge to all the atoms in a polyatomic molecule. It does not represent the actual charge. The formal charge is calculated using the formula:

Formal charge= V-N-B/2; where V is the number of valence electrons in the atom, N is the number of nonbonding electrons, and B is the total number of bonding electrons.

Atom        V        N         BFormal Charge
Carbon        4        0         84-0-8/2=0
Iodine        7        6         27-6-2/2=0

The formal charge on both carbon and iodine in CI4 is zero.

Ci4 lewis structure resonance

A single lewis structure is inadequate in cases where multiple bonds along with lone pairs are present. In these cases, the actual structure of the molecule is the average of all the lewis structures of that molecule. The lewis structures of the same molecule differ only in the arrangement of electrons. These structures are called resonating structures. In CI4, only one lewis structure is possible as no multiple bonds are present.

Ci4 lewis structure shape

VSEPR helps in predicting the shapes of the molecule. CI4 is an AX4 type molecule with four bond pair electrons and zero lone pairs around the central atom. In this case, the electron and molecular geometry are tetrahedral with bond angles of 109.5 between carbon and iodine atoms.

The four iodine atoms arrange themselves around the central atom-carbon in a tetrahedral geometry to minimize repulsion between the electron pairs between the atoms. The repulsion of electron pairs is in the order: lone pair/lone pair › lone pair/ bond pair › bond pair/ bond pair

Ci4 lewis structure angle

CI4 is a tetrahedral geometry with no lone pair hence has a bond angle of 109.5 between carbon and iodine atoms.

Ci4 hybridization

The central atom carbon has 2s22p2 configuration in the ground state and 2s12p3 in the excited state. The 2s orbital and the three 2p orbitals of carbon mix to form four sp3 hybrid orbitals with equivalent energies and 25% s character and 75% p character.

We can calculate the hybridization of any molecule by calculating the number of atoms bonded to the central atom and the number of lone pairs around it. In CI4, carbon is attached to four iodine atoms and has no lone pairs.

The steric number will be four in this case(4+0). The hybridization for steric number four is sp3. The steric number and hybridization table is given below:

                    Steric Number                      Hybridization
                            2                            sp
                            3                            sp2
                            4                            sp3
                            5                            sp3d
                            6                            sp3d2
                            7                            sp3d3

Ci4 solubility

CI4 is soluble in the following solvents:

  • Benzene
  • Naphtha
  • Formic acid
  • Carbon disulfide
  • Alcohol

Carbon tetraiodide is non-polar due to its structure. It dissolves in the non-polar solvents mentioned above due to the basic principle of solubility: like dissolves like.

Ci4 lewis structure lone pairs

Carbon belongs to group 14 and has four valence electrons. Iodine belongs to group 17 and has seven valence electrons. There are four iodine atoms in CI4. The total number of valence electrons is 4+7*4=32. Eight of the 32 valence electrons participate in covalent bonding and form four bond pairs. The rest 24 valence electrons are lone pairs, with each iodine atom having three lone pairs(six electrons).

Ci4 valence electrons

As discussed above, CI4 has a total of thirty-two valence electrons. Carbon has four valence electrons, and the other twenty-eight valence electrons are contributed by four iodine atoms(each has seven valence electrons).

Is Ci4 ionic?

No, CI4 is not ionic. It is a covalent compound with polarity in the C-I bond due to electronegativity difference. The bonds are formed by sharing electrons(as seen in covalent bonds).

Is Ci4 acidic or basic?

We can classify a substance as acid or base per Arrhenius theory, Bronsted-Lory theory, or Lewis theory. Here, we will discuss CI4 based on Lewis’s theory. CI4 is certainly not a lewis acid as carbon will not accept an electron pair(it has eight bonding electrons and no vacant orbital). It might act as a weak lewis base by donating electrons as the carbon-iodine bond is not very strong, and CI4 is not very stable.

Is Ci4 polar or nonpolar?

CI4 is non-polar despite having polar carbon-iodine bonds due to the symmetry of CI4 molecule. Carbon-iodine bonds are polar due to electronegativity differences(iodine being more polar). However, the dipole moment of all C-I bonds cancels each other out since all the atoms attached to carbon are the same(iodine), resulting in zero dipole moment. The two iodine atoms at the top will give an upward dipole moment which gets canceled by the downward moment given by the two iodine atoms at the bottom.

Zero dipole moment in CI4 due to symmetry

Is Ci4 tetrahedral?

VSEPR theory helps in predicting the shape of the molecule. Yes, CI4 has a tetrahedral electron geometry and shape. The central atom-carbon is sp3 hybridized with four iodine atoms arranged along the vertices of a tetrahedron to minimize the repulsion between electron pairs.

The repulsion between electron pairs is in the order: lone pair/lone pair › lone pair/bond pair › bond pair/bond pair. To apply the VSEPR theory, we will calculate the steric number  by counting the lone pairs and the number of atoms attached to the central atom. In CI4, carbon is the central atom attached to four iodine atoms and has no lone pair. Therefore, the steric number of carbon will be 4+0=4.

Using the calculated steric number value of four, we conclude that the hybridization of carbon is sp3 and the geometry will be tetrahedral. Since carbon has no lone pair, the shape will also be tetrahedral. The shape is the arrangement of atoms, while sgeometry is the arrangement of electron pairs(bonded and non-bonded). When no lone pairs are present on the central atom, the shape and geometry of the molecule are the same.

Is Ci4 linear?

No, CI4 is not linear. It is tetrahedral, as explained above.


Carbon tetraiodide or CI4 is a non-polar molecule with a tetrahedral shape. It is soluble in non-polar solvents. We learned about its lewis structure, shape, hybridization, formal charge, valence electrons, etc.

Sakshi Anand

Hello, I am Sakshi Anand and I am here to make chemistry easy and enjoyable to read. Complex ideas do not require complex language. I am an avid reader and enjoy researching intensively.

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