Question

Hydrogen has an electronegativity value between boron and carbon and identical to phosphorus. With this in mind, rank the following bonds in order of decreasing polarity: \(\mathrm{P}-\mathrm{H}\) , \(\mathrm{O}-\mathrm{H}, \mathrm{N}-\mathrm{H}, \mathrm{F}-\mathrm{H}, \mathrm{C}-\mathrm{H} .\)

Short answer

The bonds are ranked in order of decreasing polarity as follows: \(\mathrm{F-H > O-H > N-H > C-H > P-H}\)

Step-by-step solution

Remember the electronegativity values and difference for each bond

To rank the bonds based on polarity, we need to know the electronegativity values for each of the elements involved. Here are the electronegativity values for the elements given: - Fluorine (F): 3.98 - Oxygen (O): 3.44 - Nitrogen (N): 3.04 - Carbon (C): 2.55 - Phosphorus (P): 2.19 - Boron (B): 2.04 - Hydrogen (H): (between B and C, identical to P, so approximately 2.19) Now, we will calculate the electronegativity difference for each bond: 1. P-H: 2.19 - 2.19 = 0 2. O-H: 3.44 - 2.19 = 1.25 3. N-H: 3.04 - 2.19 = 0.85 4. F-H: 3.98 - 2.19 = 1.79 5. C-H: 2.55 - 2.19 = 0.36

Rank the bonds based on decreasing electronegativity difference

Now that we have the electronegativity difference for each bond, we can rank them in order of decreasing polarity. A higher electronegativity difference corresponds to a higher polarity. So, we arrange the bonds in the decreasing order of their electronegativity difference: 1. F-H: 1.79 2. O-H: 1.25 3. N-H: 0.85 4. C-H: 0.36 5. P-H: 0

Write the final answer

The bonds are ranked in order of decreasing polarity as follows: \(\mathrm{F-H > O-H > N-H > C-H > P-H}\)

Key concepts

Bond Polarity

In chemistry, bond polarity arises when two atoms in a chemical bond have different electronegativity values. This results in the electrons being more attracted to one atom than the other, creating a partial negative charge on one end and a partial positive charge on the other. This imbalance in electron distribution is what generates electrical dipoles, making a bond polar.
To determine bond polarity, it is crucial to understand which atoms are involved and their electronegativity values. Greater differences in electronegativity result in stronger polarity. Polar bonds are more "directional" in how they align in the environment because one side acts as a partial negative pole, and the other as a positive pole. This concept plays a significant role especially in molecules where multiple polar bonds can contribute to a molecule’s overall dipole moment.

Electronegativity Difference

Electronegativity difference is a fundamental concept for understanding bond polarity. It refers to the difference in electronegativity between two bonded atoms. The greater this difference, the more polar the bond. This is because a larger difference means that one atom has a much stronger pull on the bonding electrons compared to the other.
When the electronegativity difference is significant (greater than 1.7, typically), ionic bonds might form as one atom "steals" electrons from the other. For smaller differences, such as those below 0.5, the bond may be considered nonpolar, with electrons shared more equally between the atoms. Understanding this helps in predicting the nature of the bond whether it would be ionic, covalent, or polar covalent.

Chemical Bonds

Chemical bonds are the forces that hold atoms together in compounds. They form because atoms are more stable when they share or transfer electrons to complete their outer electron shell, also known as valence shell. The main types of chemical bonds are ionic, covalent, and metallic bonds.

• Ionic bonds occur when electrons are transferred from one atom to another, creating oppositely charged ions that attract each other.
• Covalent bonds happen when atoms share pairs of electrons. Within covalent bonds, if the sharing is unequal due to differences in electronegativity, polar covalent bonds are formed.

Learning about these bonds helps us understand material properties and reactions. For instance, covalent compounds might act as insulators, while ionic compounds can conduct electricity when dissolved in water.

Hydrogen Bonds

Even though hydrogen bonds are not true bonds like covalent or ionic bonds, they are quite significant in chemistry, especially in biological systems. They occur when a hydrogen atom covalently bonded to an electronegative atom, such as nitrogen, oxygen, or fluorine, interacts with an electronegative atom of another molecule.
Hydrogen bonds are responsible for the unique properties of water, such as its high boiling point and surface tension. They are crucial in the structure and function of biological molecules like DNA and proteins. These interactions, while weaker than covalent within the same molecule, significantly influence the shape and properties of molecules, stabilizing structures essential for life functions.