Question

Describe the hybridization of each carbon and nitrogen atom in each of the following structures

Answer 1

Clockwise from the carbon connected to three H atoms:

• C: sp³
• N: sp³
• C: sp³
• C: sp²
• N: sp².

Explanation

Start by finding the number of electron domains on each C and N atom. Why the number of electron domains? The number of electron domains of an atom indicates it hybridization. For atoms in period two (which includes both C and N):

• An atom with four electron domains is sp³ hybridized.
• An atom with three electron domains is sp² hybridized.
• An atom with two electron domains is sp hybridized.

How many electron domains on each of the atoms?

For each atom:

• Each atom that the atom in question is connected to (via covalent bonds, for sure) counts towards one electron domain. This rule shall hold for bonds of all orders. (i.e., No matter if the the two atoms are connected via a Single bond, a double bond, or a triple bond.) In other words, each C-C or C-N single bond counts towards one electron domain. Each C=N double bond also counts towards one electron domain.
• Each lone pair on the atom in question counts towards one electron domain. Keep in mind that there are two electrons in one lone pair. (Hence the name "pair".)

For example:

• The carbon atom at the bottom of the graph is connected to four other atoms- three Hs and one N. There's no lone pair on that atom. That C atom contains four electron domains, which implies that the atom is sp³ hybridized.
• The nitrogen atom near the right end of the molecule is connected to two other atoms- one C and one H. There's one lone pair on that molecule. 2 + 1 = 3. That N atom contains three electron domains, which implies that the atom is sp² hybridized.

Try to figure out the number of electron domains on the rest of the atoms. Then determine their hybridization. In conclusion, clockwise from the carbon connected to three H atoms:

• C: sp³
• N: sp³
• C: sp³
• C: sp²
• N: sp².