Urea: (NH2)2CO
1. Which bonds in the molecule are polar and which are nonpolar?
2. What is the most polar bond in the molecule?
POLAR
1. In the molecule urea (NH2)2CO, the N-H bonds and the C=O bond are polar, while the N-C and C-N bonds are nonpolar.
2. The most polar bond in the molecule is the C=O bond.
To determine which bonds in the urea molecule are polar and nonpolar, we need to consider the electronegativity difference between the atoms involved in each bond.
1. Polar bonds occur when there is an electronegativity difference between the atoms involved. The greater the electronegativity difference, the more polar the bond. In urea, we have four different bonds:
a) The N-H bond: Nitrogen (N) has an electronegativity of 3.04, and hydrogen (H) has an electronegativity of 2.2. Since there is a significant difference (3.04 - 2.2 = 0.84), the N-H bond is polar.
b) The C=O bond: Carbon (C) has an electronegativity of 2.55, and oxygen (O) has an electronegativity of 3.44. The electronegativity difference (3.44 - 2.55 = 0.89) indicates that the C=O bond is polar.
c) The N-C bond: Nitrogen (N) and carbon (C) have electronegativity values of 3.04 and 2.55, respectively. The electronegativity difference (3.04 - 2.55 = 0.49) suggests that the N-C bond is polar, but less polar than the N-H and C=O bonds.
d) The N-H bond: Nitrogen (N) and carbon (C) have electronegativity values of 3.04 and 2.55, respectively, suggesting a smaller electronegativity difference (3.04 - 2.55 = 0.49). Therefore, the N-C bond is also polar, but less polar than the N-H and C=O bonds.
Considering the above information, the polar bonds in urea are the N-H bond, the C=O bond, and the two N-C bonds. The N-H and C=O bonds are more polar than the N-C bonds.
2. To determine the most polar bond in the molecule, we compare the electronegativity differences of the polar bonds. The bond with the greatest electronegativity difference will be the most polar. In this case, the bond with the highest difference is the C=O bond (0.89), making it the most polar bond in the urea molecule.