Question 4.45

[Cassidy 1G]

Hi, can someone please explain how to get the answer to this question? "Describe the structure of the formaldehyde molecule CH2O in terms of hybrid orbitals, bond angles, and sigma and pi bonds." C is the central atom.

[Joshua Hughes 1L]

First draw out the Lewis structure with Carbon at the center, single bonds between C and the Hydrogens and a double bond between C and O. Seeing that there are three atoms that carbon is bound to we know this is trigonal planar and that the bond angles are all expected to be 120 degrees.
Then figure out the hybridization of carbon which should be sp^2 because there are 3 regions of electron density around the carbon. Now using our knowledge about the hydration we can then say for the double bond with C and O one will be sigma the other will be a π bond. Then note that all the single bonds are sigma bonds.

[Suchita 2I]

The CH2O molecule has C as the central atom with a single bond with each H atom and a double bond with the O atom. This gives 3 regions of electron density around the C atom and therefore, sp2 hybridization. This gives a triangular planar shape with 120 degree bond angles. There are 3 sigma bonds (2C 2sp2-H 2s and 1 C 2sp2-O 2p) and 1 pi bond (C 2p-O 2p).