Chclo Lewis Structure,Characteristics:13 Must To Know Facts

In this article chclo lewis structure and other important facts are discussed.

Formyl chloride, CHClO is formed by the replacement of hydroxyl group by a halogen atom like chlorine. It is a compound with molecular mass of  64.47g/mol with boiling point 46.40C.  It is formed by the photolytic reaction of formaldehyde with chlorine in low temperature.

Lewis structure of Formyl Chloride,CHClO

The bond made in this formyl chloride is not all single bonds. There is one double bond existing between carbon and oxygen and rest were single bonds. So the Lewis structure of formyl chloride should be drawn by keeping that in mind.
The Lewis structure of any molecule is drawn for getting better knowledge about its bond formation. It is drawn through by taking the symbols of elements along with dots as their valence electrons, bonds as certain lines. So we easily get idea about the number of bonds formed and electrons involved.
Carbon is the central atom surrounded with hydrogen, Oxygen and chlorine. So carbon is written in central with all other atoms. Their valence electrons are also represented.

chclo lewis structure
Valence electrons in CHClO

In the next step carbon forms two bonds with oxygen and one each with hydrogen and chlorine.

Resonance in Formyl Chloride,CHClO

The motion of electrons involved in a bond results different structures to a molecule . That structures are called resonating structures and process is called resonance. There is no resonance structure for formyl chloride but it’s carbocation named acylium cation has more than one structure.

When the chlorine atom leaves by taking  the electrons shared with carbon, a carbocation is formed. This carbo cation involves in resonance . It is shown below.

Resonance in Acylium Cation

Octet Rule in Formyl Chloride,CHClO

Let’s discuss about octet rule in formyl chloride. Carbon, oxygen and Chlorine obeys octet rule. Carbon has four valence electrons in outer shell. When it forms bond with oxygen it gets two more electrons. When forms bond with hydrogen and chlorine again two electrons are added into its orbital. So in total it gets eight electrons in the valence shell.

Similarly chlorine and oxygen has seven and six electrons respectively in their valence shell got eight after making bond with carbon. Hydrogen is found to be an exception from octet rule it needs only two electrons for stable existence and it is obtained from carbon through bond making.

Therefore oxygen, carbon and chlorine obeys octet rule and are stable now. But hydrogen doesn’t obey octet rule but it has a stable existence.

Octet Rule in CHClO

Shape and angle in Formyl Chloride,CHClO

The shape of formyl chloride is triagonal planar. The shape of molecule is determined by VSEPR theory. According to this theory atoms occupy their position in such a way to reduce the repelsion from other atoms. Here the central carbon is attached with chlorine, oxygen and hydrogen. Except hydrogen both the atoms has lone pairs.

So to minimise the repelsion between these electrons the atoms will stay as far as possible to maintain a good geometry. So it acquires triagonal planar geometry with 1200. A triagonal planar model has one atom in the middle with all the three other atoms are situated in the corners of a triangle. All the atoms are in a single plane and the angle between every bond will be 1200.

Shape and Angle of CHClO

Formal charge of Formyl Chloride,CHClO

The charge given for every atom in a molecule after bond making is called formal charge . It’s value can be either positive or negative. Sometimes it can be zero. The equation for its calculation is

Formal charge =valence electrons – no of dots- no of bonds
Formal charge of carbon = 4-0-4 = 0

Formal charge of  Chlorine = 7-6-1 = 0

Formal charge of oxygen = 6-4-2=0

Formal charge of hydrogen = 1-0-1 = 0

 Therefore formal charge in formyl chloride is zero. So formyl chloride is a neutral compound.

Lone pairs in Formyl Chloride,CHClO

In the below figure some of the electrons are not involved in bond formation. They stay as it is . It is called lone pair of electrons. Here chlorine and oxygen has lone pairs. Chlorine has three and oxygen with two. That is total five lone pairs are found.

Lone pairs in CHClO

Valence Electrons in Formyl Chloride,CHClO

The total outer electrons which played a major role in bond construction is called it’s valence electrons. Sometimes no all valence electrons participate in bond making. Some will stay as lone pair. The total number of valence electrons in formyl chloride is 18.

Hybridisation in Formyl Chloride,CHClO

Formyl chloride molecule follows sp2 hybridization. Valence orbitals with same energies are undergoing hybridization to form new orbitals.
Carbon atom with ground state configuration is 1s2 2s2 2p2 . When one of the electron is promoted to 2p level there is one 2s and three 2p orbitals are available with one electron each.

In which only one 2s and two 2p orbitals undergo hybridization to form three sp2 orbitals. Then they overlapps axially with the orbitals of oxygen, hydrogen and chlorine to form three bonds. All those three bonds are Sigma bonds.

Then the unhybridised 2pz orbital of carbon overlapps sidewise with similar orbital of oxygen to form a pi bond. Therefore formyl chloride undergo sp2 hybridization to give a molecule with triagonal planar shape and 1200 is found to be the angle between the bonds made there.

Hybridisation in CHClO

Solubility in Formyl Chloride,CHClO

Formyl chloride is an unstable compound. It is due to the formation of hydrogen chloride,HCl. The chlorine present in formyl chloride is a best leaving group, which leaves with the bonded electrons to make acylium cation. Then the acidic hydrogen easily got removed from the carbon to neutralise it’s positive charge.

Then the hydrogen and chlorine combines to form HCl and the remaining form carbon monoxide,CO. So it is not stable and suddenly got dissociated it’s isolation is not possible. Therefore its solubility can be distinguished in any solvents. Due to its polar nature it may be get dissolved in water.

Is Formyl Chloride,CHClO Polar or not ?

Formyl chloride is a polar molecule. There exist three polar bonds that is C-Cl, C-H,C-O. The electronegativity difference of carbon chlorine and carbon oxygen bond is 0.45 and 0.89 respectively. In carbon hydrogen bond it is 0.45. Due to the formation of polar bond between carbon and chlorine it can be a polar molecule.

Is Formyl Chloride,CHClO Ionic or not ?

Formyl chloride is purely a covalent compound made by sharing electrons between carbon, hydrogen, chlorine and oxygen. It follows sp2 hybridization.

Is Formyl Chloride,CHClO Acidic or not ?

Formyl chloride is an acidic compound. It is because when the leaving group chlorine leaves with the electron there creates a carbocation called acylium cation. To neutralise the charge of carbon the hydrogen tends to leave as H+ ion. We all know that compound which donates H+ ions is found to be good acids. So formyl chloride is a good acid. The left hydrogen and chlorine then forms HCl.


From this article we understood that formyl chloride is polar molecule with three Sigma bonds and one pi bond. It is a covalent compound which follows sp2 hybridization. It’s molecular geometry is triagonal planar with an angle of 1200.  Due to formation of carbon monoxide and HCl, formyl chloride’s purification and it’s characterisation was not possible. Therefore it exist as an unstable molecule.

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