Question

The most polar bond is: (a) \(\mathrm{O}-\mathrm{H}\) (b) \(\mathrm{C}-\mathrm{O}\) (c) \(\mathrm{C}-\mathrm{Br}\) (d) \(\mathrm{C}-\mathrm{C}\)

Short answer

The most polar bond is (a) \( \mathrm{O}-\mathrm{H} \).

Step-by-step solution

Understand Polarity

Polarity in a bond is determined by the difference in electronegativity between the two atoms involved in the bond. The greater the difference, the more polar the bond.

Electronegativity Values

Check the electronegativity values of the atoms involved: Oxygen (O) is about 3.44, Hydrogen (H) is about 2.20, Carbon (C) is about 2.55, and Bromine (Br) is about 2.96. Use these values to calculate the differences.

Calculate Electronegativity Differences

Calculate the electronegativity differences for each bond:- \( \mathrm{O}-\mathrm{H} \): \|3.44 - 2.20\| = 1.24- \( \mathrm{C}-\mathrm{O} \): \|3.44 - 2.55\| = 0.89- \( \mathrm{C}-\mathrm{Br} \): \|2.96 - 2.55\| = 0.41- \( \mathrm{C}-\mathrm{C} \): \|2.55 - 2.55\| = 0

Compare Differences

Compare the electronegativity differences. The bond with the greatest difference will be the most polar.- \( \mathrm{O}-\mathrm{H} \) has the greatest difference of 1.24.

Key concepts

Electronegativity

Electronegativity is a measure of how strongly an atom can attract or pull electrons towards itself in a chemical bond. It's a critical concept in understanding how atoms interact in molecules. Each element has a specific electronegativity value, which helps us predict the behavior of atoms in chemical reactions.

When two atoms form a bond, the difference in their electronegativity values determines how the electrons are shared. A large difference means one atom will pull the electrons more strongly, leading to an unequal sharing of the electrons. This results in a polar bond. For example, in the \( \mathrm{O}-\mathrm{H} \) bond, oxygen has a higher electronegativity than hydrogen, which makes the bond polar.

It's important to note that electronegativity values are usually represented on a scale, with higher values indicating a stronger pull of electrons. Recognizing these differences is crucial when analyzing molecule properties and predicting their reactivity.

Polar Bonds

Polar bonds are the results of differences in electronegativity between bonded atoms. When electrons are unequally shared in a bond, due to significant electronegativity differences, the result is a bond that has a positive and a negative pole, or a dipole. This makes the molecule polar, meaning it has a partial positive charge on one end and a partial negative charge on the other.

A polar bond can be likened to a tiny magnet, with one end slightly positive and the other slightly negative. For example, in the \( \mathrm{O}-\mathrm{H} \) bond, oxygen draws the electrons closer to itself. This results in oxygen having a slight negative charge, while hydrogen has a slight positive charge.

Such polar bonds impact the physical properties of compounds like boiling points and solubility in water. They also play key roles in chemical reactivity, often leading to hydrogen bonding and other intermolecular interactions that are vital in the structure and function of complex molecules.

Chemical Bonding

Chemical bonding is the process by which atoms combine to form molecules. The type of bond formed depends on the elements involved and their specific properties, such as electronegativity. There are several types of chemical bonds including ionic, covalent, and metallic bonds, but understanding electronegativity differences is key in predicting the nature of these bonds.

Covalent bonds are formed when two nonmetals share electrons, and they can be either polar or nonpolar. A polar covalent bond arises if the atoms involved have different electronegativities, leading to unequal sharing of electrons. Nonpolar covalent bonds occur when atoms have similar electronegativities, such as the \( \mathrm{C}-\mathrm{C} \) bond, where electrons are shared equally.

Understanding chemical bonding is essential for predicting molecular structure, geometry, and reactivity in chemical reactions. It explains why certain molecules are more stable, how they will behave under certain conditions, and why they interact with other substances the way they do. This knowledge is foundational in fields ranging from chemistry and biology to materials science and engineering.