CH4O is the condensed structural formula for methanol (CH3OH). It is polar as it consists of a strongly polar hydroxyl (OH) functional group.
The strong dipole moments of the O-H and C-O bonds do not get canceled equally with the small dipole moments of three weakly polar C-H bonds.
CH4O consists of 3 C-H bonds, 1 C-O bond, and an O-H bond.
Each C-H bond is only weakly polar (almost non-polar as per Pauling’s electronegativity scale), possessing an electronegativity difference of only 0.35 units between the single covalently bonded carbon (E.N = 2.55) and hydrogen (E.N = 2.20) atoms.
The shape of the molecule w.r.t the C-atom in the methyl (CH3) group is tetrahedral.
The C-O bond is moderately polar as per an electronegativity difference of 0.89 units between the carbon and oxygen (E.N = 3.44) atoms.
In contrast, the O-H bond is strongly bonded as per an electronegativity difference of 1.24 units between the oxygen and hydrogen atoms, respectively.
2 lone pairs of electrons present on the oxygen atom lead to strong lone pair-lone pair and lone pair-bond pair repulsions, thus distorting the shape and geometry of the molecule.
Oxygen being strongly electronegative, attracts the C-H bonded electrons in addition to attracting the C-O and O-H bonded electrons.
The charged electron cloud stays non-uniformly spread over the molecule.
The O-atom thus gains a partial negative charge (δ–) while the C-atom gains a partial positive charge (δ+), while each of the terminal H-atoms gains δ++ charges.
It is due to the bent in the above molecular shape that the dipole moments of individually polar bonds stay uncancelled overall.
Consequently, CH4O is overall polar witH a resultant non-zero dipole moment (net µ > 0).
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