Why is it that identical functional groups on different molecules don't have identical frquencies?
Why does the O- H frequency occur at a value higher than the C=bond?
a. The mass of the atom makes a difference.
b. what is attached makes a difference.
c. bending and stretching frequencies are different.
d. different kinds of electrons (sigma versus pi for example) make a difference.
The frequencies of identical functional groups on different molecules can vary due to several factors, including differences in molecular environment, molecular size, and molecular interactions. These factors affect the bond strengths and vibrational motions of the functional groups, leading to variations in their frequencies.
To understand why the O-H frequency occurs at a value higher than the C=C bond, we need to consider the differences in bond strength and molecular interactions.
The O-H bond is generally stronger and more polar than the C=C bond, which means that it requires more energy to vibrate. This higher bond strength leads to a higher frequency of vibration for the O-H functional group compared to the C=C functional group.
Moreover, the O-H bond is typically involved in hydrogen bonding interactions, where the oxygen atom forms a weak bond with another hydrogen or nitrogen atom. These hydrogen bonding interactions further influence the vibrational motion of the O-H group, resulting in an increase in the O-H frequency. The C=C bond, on the other hand, is usually not involved in such strong intermolecular interactions, leading to a lower frequency.
In summary, the differences in bond strength and molecular interactions contribute to the variation in frequencies between identical functional groups on different molecules. The O-H frequency occurs at a higher value than the C=C bond due to the stronger bond strength and involvement in hydrogen bonding interactions.