Question

Hydrogen bonds differ from covalent bonds in that a. covalent bonds can form between any type of atom, and hydrogen bonds form only between \(\mathrm{H}\) and \(\mathrm{O}\). b. covalent bonds involve sharing of electrons, and hydrogen bonds involve the complete transfer of electrons. c. covalent bonds result from equal sharing of electrons, but hydrogen bonds involve unequal sharing of electrons. d. covalent bonds involve sharing of electrons between atoms, but hydrogen bonds are the result of weak attractions between a hydrogen atom of a polar molecule and an electronegative atom of another polar molecule. e. covalent bonds are weak bonds that break easily, but hydrogen bonds are strong links between atoms that are not easily broken.

Short answer

The correct answer is d. Covalent bonds involve sharing of electrons between atoms, but hydrogen bonds are the result of weak attractions between a hydrogen atom of a polar molecule and an electronegative atom of another polar molecule.

Step-by-step solution

Understanding Covalent and Hydrogen Bonds

A covalent bond is formed when two atoms share one or more pairs of electrons. On the other hand, a hydrogen bond is a weak type of bond that forms between a hydrogen atom of one molecule and a more electronegative atom of another molecule. The electronegative atom can be oxygen, nitrogen, or fluorine of a different molecule.

Analyzing Each Statement

Evaluate each statement given in the problem to see which one correctly describes the distinction between a covalent bond and a hydrogen bond.

Statement Analysis

Choose the statement that accurately defines these two types of bonds. Consider their formation, the atoms involved, and the interaction of electrons.

Identify the Correct Statement

Option d is correct. Covalent bonds involve sharing of electrons between atoms, but hydrogen bonds are the result of weak attractions between a hydrogen atom of a polar molecule and an electronegative atom of another polar molecule. This is the fundamental difference between a covalent bond and a hydrogen bond

Key concepts

Covalent Bonds

Covalent bonds are essential components of molecules, formed when two atoms share pairs of electrons. This type of bond often occurs between nonmetals. For example, in a water molecule (H₂O), the oxygen atom shares electrons with two hydrogen atoms, creating two covalent bonds.
This sharing allows each atom to achieve a stable electronic configuration, similar to that of a noble gas.

• Each shared pair of electrons constitutes one covalent bond.
• Sometimes, atoms share multiple pairs of electrons, leading to double or triple bonds.
• The strength of a covalent bond depends on the overlap of orbitals and the atoms involved.

Covalent bonds are considered strong due to the substantial energy required to break them. Nevertheless, varying degrees of sharing exist, depending on the atoms' electronegativities. Generally, in a classic covalent bond, sharing is almost equal.

Hydrogen Bonds

Hydrogen bonds are significantly weaker than covalent bonds, yet they are crucial for many biological and chemical processes. These bonds occur when a hydrogen atom, which is covalently bonded to an electronegative atom like oxygen, nitrogen, or fluorine, experiences a weak attraction towards another electronegative atom in a different molecule.
This can be observed in the properties of water, where hydrogen bonds give water its unique characteristics, such as its high boiling point and surface tension.

• Hydrogen bonds are intermolecular, meaning they occur between molecules.
• They are important in the structure and function of macromolecules like DNA and proteins.
• Despite their weak nature individually, collectively, they can have a significant impact.

Understanding hydrogen bonds is essential for grasping concepts in various scientific fields, including biology, chemistry, and physics.

Electronegativity

Electronegativity is a chemical property that describes an atom's ability to attract and hold onto electrons. Different elements have different electronegativities, influencing how they bond with other atoms. When atoms form bonds, their electronegativities affect the electron distribution, impacting the bond type and strength.
Elements like fluorine, oxygen, and nitrogen are highly electronegative. This high electronegativity results in a strong pull on electrons away from less electronegative atoms, creating polar covalent bonds when bonded with atoms like hydrogen.

• The difference in electronegativity between atoms determines a bond's polarity.
• Bonds between atoms with similar electronegativities tend to be nonpolar.
• As the difference increases, the bond becomes more polar, leading to dipole interactions like hydrogen bonds.

Electronegativity scales, like the Pauling scale, allow scientists to predict the nature of bonds and molecular interactions.