CH₂O Polar or Nonpolar

Formaldehyde is a colourless gas that is an organic compound with the chemical formula CH₂O. It is the most common and basic aldehyde, composed of two hydrogens, one carbon and one oxygen.

Carbon has four valence electrons, three of which are sp² hybridised, resulting in two C – H and one C – O bond. The fourth carbon electron remains unhybridized, forming a “bond (Pi bond)” with an oxygen electron. This arrangement results in H₂C=O. Carbon and oxygen have a double bond, which consists of one pi-bond and one sigma-bond. The sigma bond is stronger than the pi bond.

Formaldehyde (methanal) has a “trigonal planar” structure and a bond angle of 120° according to Valence Shell Electron Repulsion Theory (VSEPR).

Table of Contents

• Is CH₂O Polar or Nonpolar?
• Electronegativity of CH₂O
• How to Check Polarity of a Molecule?
• Frequently Asked Questions – FAQs

Is CH₂O Polar or Nonpolar?

The difference in electronegativity and electron sharing between two atoms in a covalent bond determines whether the molecule is polar or non-polar.

When the sharing of electrons between two atoms is unequal, the molecule is said to be polar, and when the sharing of electrons between the atoms is equal, the molecule is said to be non-polar.

Formaldehyde (CH₂O) is a polar compound. This is because of the unbalanced electron density. The electronegativity difference between hydrogen and carbon is negligible, whereas the electronegativity difference between carbon and oxygen is large enough to cause polarity.

This means that electrons in the double bond are more attracted to oxygen, causing charges to shift, resulting in a partial positive charge on the carbon and a partial negative charge on the oxygen.

The difference in electronegativity allows polarity to make a molecule non-symmetrical (asymmetrical), allowing the -ve charge to be centralised on one side of the molecule by the oxygen.

Electronegativity of CH₂O

The CH₂O molecule is made up of one carbon, one hydrogen, and two oxygen atoms. Carbon has an electronegativity of 2.55, hydrogen has a value of 2.2, and oxygen has a value of 3.44. As a result, oxygen is the most electronegative component of the formaldehyde molecule. This is why oxygen pulls the bonded electron pair to one side of the atom. Since the oxygen atom is connected to the carbon atom via a double bond, the intensity of electrons increases on the oxygen atoms.

Read more: Lewis Structure of HCHO

How to Check Polarity of a Molecule?

There are some factors that can help determine whether a molecule is polar or non-polar, and they are as follows:

1. Dipole Moment – It is a measurement of the distance between two opposing electrical charges. The greater the value of the dipole moment, the greater the polarity of the molecule. All non-polar molecules have a dipole moment of “0,” whereas polar molecules always have a dipole moment that is “non-zero.”

2. Electronegativity – An atom’s electronegativity is its ability to attract bonded electron pairs to its side. The greater an atom’s electronegativity, the closer it attracts the bonded electron pair.

3. Geometrical Shape – The charges on the atoms of polar molecules are seen to be unevenly distributed because they are asymmetric.

On the other hand, nonpolar molecules are symmetrical in shape, so the charge balance on all atoms remains equal.