Is CCl4 polar or nonpolar? - Polarity of Carbon tetrachloride

CCl₄ is the chemical formula for the colorless, sweet-smelling liquid called carbon tetrachloride, also sometimes known as tetrachloromethane.

Tetra means four so by carbon tetrachloride we understand that four chlorine atoms are attached to a carbon in this molecule.

The question that we are here to address is whether CCl₄ is polar or nonpolar in nature. So, let us find out immediately.

Is CCl₄ polar or nonpolar? 

Carbon tetrachloride (CCl₄) is a non-polar molecule. There are four C-Cl polar bonds present in CCl₄. The polarity of each bond is attributed to a significant electronegativity difference between the two bonded atoms.

The whole molecule however is non-polar due to its symmetric, tetrahedral shape. Thus, CCl₄ is a non-polar molecule overall with a net dipole moment, µ =0.

Name of molecule	Carbon tetrachloride (CCl4)
Bond type	Polar covalent
Molecular geometry	Tetrahedral
Polar or Non-polar?	Overall nonpolar molecule
Dipole moment	Zero
Bond angle	109.5º

The answer given above makes us think about the following three factors that control the polarity of molecules:

• Electronegativity
• Dipole moment
• Molecular geometry or shape

To make things easier for you, we have discussed the role of all three factors in turning out CCl₄ as a non-polar molecule in the section below.

Factors affecting the polarity of CCl₄

Electronegativity 

Chlorine (Cl) is a halogen present in group VII-A (or group 17) of the Periodic Table. It has 7 valence electrons, so it is extremely hungry to gain one more electron and achieve a stable, octet electronic configuration.

This extreme electron affinity is called the high electronegativity of chlorine.

Electronegativity is the ability of an elemental atom to attract a shared pair of electrons from a covalent bond.

Atom	Electronic configuration	Valence electrons
Carbon (6C)	1s2 2s2 2p2	4
Chlorine (17Cl)	1s2 2s2 2p63s23p5	7

All covalent bonds with electronegativity differences greater than 0.5 between bonded atoms are essentially polar in nature. Greater the electronegativity difference, the higher the bond polarity.

Cl (E.N= 3.16) is more electronegative than C (E.N= 2.55). Due to the high electronegativity of Cl, chlorine strongly attracts the shared electron cloud from each C-Cl bond in the CCl₄ molecule.

There is an electronegativity difference of 3.16 – 2.55 = 0.61 units.

Therefore, the shift of the C-Cl shared electron cloud toward the chlorine atom to a larger extent develops oppositely charged poles in the CCl₄ molecule.

Chlorine gains a partial negative (Cl^δ-) charge due to a slight excess of electrons. While each carbon atom develops a partial positive charge (C^δ+) due to slight electron deficiency.

Thus, each C-Cl bond in the CCl₄ molecule is individually a polar bond. This is called the bond polarity of CCl₄.

Dipole moment

The dipole moment is a vector quantity that represents the polarity of a bond and/or a molecule.

It has a symbol µ and is defined as the product of electrical charge (Q) and charge separation i.e., bond length (r). Debye (D) is the symbol used for dipole moment.

⇒ µ= Q.r

In chemistry, the dipole moment arrow is pointed from the positive end to the negative center by convention.

The charge separation is measured from the center of the positive pole to the
center of the negative pole, technically the bond length.

Q is measured in Coulombs (C) while r is calculated in the unit of distance i.e., meters (m). So, 1 Debye (D) dipole moment = 3.335 X 1030 C.m.

The dipole moment of each C-Cl bond in the CCl₄ molecule points from C^δ+ to Cl^δ-. It has a µ value approximately equal to the electronegativity difference between the bonded atoms.

Molecular geometry

Each C-Cl bond in the CCl₄ molecule is polar with a specific dipole moment value, this makes us wonder why is then CCl₄ a non-polar molecule overall.

Well, here is where there is a dominant role of this third very important factor i.e., the geometry and shape of the CCl₄ molecule.

In CCl₄, 4 chlorine atoms are bonded to a carbon atom in the center through single covalent bonds. Each Cl shares 1 valence electron while the C atom shares all 4 of its valence electrons for bond formation.

In this way, all the bonded atoms achieve an octet configuration in the CCl₄ molecule.

According to the Valence Shell Electron Pair Repulsion (VSEPR) theory of chemical bonding, CCl₄ is an AB4-type molecule.

One atom of C (A), and four atoms of Cl are bonded (B). There is no lone pair on the central A atom.

Thus, CCl₄ has a symmetric, tetrahedral geometry or shape.

The net dipole moment effect of three C-Cl bonds, pointing downwards (blue arrow) gets canceled with the dipole moment of a C-Cl bond, pointing upwards in the tetrahedron (red arrow).

This cancelation of dipole moments in opposite directions makes CCl₄ a non-polar molecule overall with a net dipole moment value µ=0. CCl₄ has a mutual bond angle of 109.5 °.

Difference between polar and non-polar molecules

Polar molecule	Non-polar molecule
Atoms having a difference in electronegativity	Atoms may have the same or different electronegativity values
Unequal charge distribution overall	Equal charge distribution overall
Net dipole moment greater than 0	Net dipole moment equals to zero
Examples include water (H2O), hydrogen sulfide (H2S), ammonia (NH3) and sulfur dioxide (SO2), etc.,	Examples include oxygen (O2), nitrogen (N2), methane (CH4), and carbon tetrachloride (CCl4).

Also check –

• CCl4 lewis structure, molecular geometry, bond angle
• How to tell if a molecule is polar or nonpolar?
• Is SF4 polar or nonpolar?
• Is CO2 polar or nonpolar?
• Is NH3 polar or nonpolar?
• Is SO2 polar or nonpolar?
• Is SO3 polar or nonpolar?
• Is H2O polar or nonpolar?
• Is H2S polar or nonpolar?
• Is HCN polar or nonpolar?
• Is XeF4 polar or nonpolar?
• Is CH2O polar or nonpolar?
• Is CHCl3 polar or nonpolar?
• Is BrF5 polar or nonpolar?
• Is SF6 polar or nonpolar?
• Is BF3 polar or nonpolar?
• Is PCl5 polar or nonpolar?

FAQ

Why CCl4 is a nonpolar molecule?

CCl4 has polar bonds present due to an electronegativity difference greater than 0.5 units between bonded C and Cl atoms. The dipole moments of C-Cl bonds get canceled in opposite directions due to the symmetric, tetrahedral shape of CCl4. Therefore, CCl4 is a non-polar molecule overall with a net dipole moment = 0.

Why does CCl4 have a higher boiling point than CHCl3 even though CCl4 is nonpolar and CHCl3 is polar?

The boiling point of carbon tetrachloride is 76.7° while that of chloroform (CHCl3) is 61.2°. CCl4 is a symmetrical, compactly packed molecule. Thus, there is a greater surface area of contact between CCl4 molecules which allows more extensive intermolecular forces of attraction as compared to the intermolecular forces of attraction present in CHCl3. So CCl4 has a higher boiling point.

What will be the order of polarity and its reason in CH3Cl, CH2Cl2, CHCl3, and CCl4?

Increasing order of polarity: CCl4 < CHCl3 < CH2Cl2 < CH3Cl CCl4 has polar bonds present but it is an overall non-polar molecule due to its symmetric tetrahedral shape and geometry. The other three compounds also have a tetrahedral geometry, but their charge distribution is not balanced. In CHCl3, the 3 Cl atoms attract the C-H electron cloud in addition to attracting each CCl shared electron pair, so it has a dipole moment value of 1.08 D. In CH2Cl2, there are two C-H and two C-Cl bonds. The two Cl atoms attract all the shared electron clouds, so it has a larger dipole moment of 1.67 D. CH3Cl is the most polar with a dipole moment of 1.87 D. A single Cl and three C-H bonds mean the strongest electron-attracting effect of the electronegative Cl atom. None of the dipole moments get canceled.

Why is NH3 polar and CCl4 nonpolar?

NH3 has an asymmetric trigonal pyramidal shape or geometry. There is a lone pair on nitrogen which leads to the asymmetric shape. The dipole moment effect of individual N-H bonds adds up which makes the overall NH3 molecule polar with a net dipole moment of 1.4 D. CCl4 has polar C-Cl bonds present, but the molecule overall is non-polar due to its symmetric tetrahedral shape. Individual dipole moments get canceled in opposite directions so µ (CCl4 ) = 0.

Does CCl4 dissolve with nonpolar or polar substances?

CCl4 is a non-polar organic solvent. As a general rule-of-thumb, like dissolves like so CCl4 dissolves non-polar substances and vice versa. Accordingly, CCl4 is miscible with non-polar solvents like hexane while largely immiscible with methanol (a polar solvent).

What is the formal charge present on CCl4?

There is no formal charge present on CCl4. The oxidation state of carbon is +4 while that of chlorine is -1. Four chlorine atoms attached make the overall negative charge = 4 (-1) = -4. +4 gets canceled with -4. S0, CCl4 is a neutral molecule with 0 formal charges.

How many lone pairs are present on central carbon in CCl4?

Number of lone pairs on C = [ Valence electrons of C – Number of atoms attached to C ]/2 ∴  Lone pairs = (4 – 4)/2 = 0. So, no lone pair is present on carbon in CCl4

Explain hybridization in CCl4?

The central carbon in CCl4 is sp3 hybridized. The electronic configuration of carbon is 1s22s22p2. One 2s electron shifts to 2p. The 2s orbital hybridizes with the three 2p orbitals to produce four sp3 hybrid orbitals during chemical bond formation in CCl4. Each sp3 has one electron ready for bonding. The electronic configuration of chlorine is 1s22s22p63s23p5. The 3p orbitals of Cl have electrons placed as 3px23py23pz1. So, Cl uses the p orbital containing a single unpaired electron to form a sigma bond with an sp3 hybrid orbital of C. Thus, each C-Cl bond in the CCl4 molecule is formed by an sp3 -p overlap.

Summary

• Carbon tetrachloride (CCl₄) is a non-polar molecule with µ=0.
• Due to an electronegativity difference of 0.61 units between bonded C and Cl atoms, each C-Cl bond in the CCl₄ molecule is polar.
• The dipole moments of individual C-Cl bonds get canceled in opposite directions due to the symmetric tetrahedral molecular geometry.
• The overall charge distribution in the CCl₄ molecule is balanced.
• The C-Cl bond length in the CCl₄ molecule is 178 pm.
• CCl₄ has a mutual bond angle of 109.5°.