Problem 12 - Chemistry A Guided Inquiry

Question

For \(\mathrm{H}_{2} \mathrm{CO}\) : a) Is the sum of the bonding electrons and lone pair electrons around the carbon atom consistent with the Lewis model? b) Is the sum of the bonding electrons and lone pair electrons (nonbonding electrons) around the oxygen atom consistent with the Lewis model?

Step-by-Step Solution

Answer

According to the Lewis model, both Carbon and Oxygen in \(\mathrm{H}_{2} \mathrm{CO}\) are in stable configuration. Carbon has 4 bonding electrons, consistent with the model. Oxygen has 4 bonding electrons and 2 lone pair (nonbonding) electrons, also consistent with the model.

Step 1: Drawing the Lewis Structure

Start by drawing the Lewis dot structure of \(\mathrm{H}_{2} \mathrm{CO}\). Carbon is the less electronegative atom, so, it will be the central atom surrounded by Hydrogen atoms and Oxygen atom. Hydrogen atoms form single bonds with Carbon and there is a double bond between Carbon and Oxygen. Write the remaining 2 electrons on oxygen as a lone pair.

Step 2: Evaluate carbon atom according to the Lewis model

According to Lewis model, an atom is most stable when its outermost shell is full. For carbon, the second shell is the outermost shell and can hold 8 electrons. It needs 4 more electrons to complete its octet. In \(\mathrm{H}_{2} \mathrm{CO}\), Carbon shares 1 electron with each hydrogen atom through single bonds and 4 electrons with oxygen through a double bond. So, the sum of the bonding electrons around the carbon atom is 4 to form covalent bonds, which result is consistent with the Lewis model.

Step 3: Evaluate oxygen atom according to the Lewis model

In \(\mathrm{H}_{2} \mathrm{CO}\), Oxygen shares 4 electrons with carbon through a double bond, and it also has 2 lone pair electrons. Hence, the total sum of the bonding and nonbonding electrons around Oxygen is 4 + 2 = 6. This is consistent with the Lewis model as Oxygen needs 2 more electrons to complete its octet, which in this case it achieves through making covalent bonds with Carbon.