Hydrogen Bonding
Hydrogen Bonding - Related Videos
01:04
Hydrogen Bonds
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2025
A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another polar molecule, such as water (H2O), hydrogen fluoride (HF), or ammonia (NH3). The huge electronegativity difference between the H atom (2.1) and the atom to which it is bonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for an N atom), combined with the very small size of an H atom...
00:26
Hydrogen Bonds
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2026
Hydrogen BondsHydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.Hydrogen Bonds Control the World!Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are...
01:23
IR Spectrum Peak Broadening: Hydrogen Bonding
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2024
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1. However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
06:06
Hydrogenation
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2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the hydrogenation of chalcone as an example of an alkene hydrogenation reaction (Figure 1). In this experiment, palladium on carbon (Pd/C) will be used as a heterogeneous catalyst for the process. A balloon will be used to supply the hydrogen atmosphere. Figure 1: Diagram showing the hydrogenation of chalcone to 3-phenylpropiophenone.
02:45
Valence Bond Theory
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2020
Overview of Valence Bond Theory Valence bond theory describes a covalent bond as the overlap of half-filled atomic orbitals (each containing a single electron) that yield a pair of electrons shared between the two bonded atoms. The orbitals on two different atoms overlap when a portion of one orbital and a portion of a second orbital occupy the same region of space. According to valence bond theory, a covalent bond results when two conditions are met: (1) an orbital on one atom overlaps an...
FAQs
The interaction depends on differences in electronegativity between covalently bonded atoms. These differences create partial charges, allowing the hydrogen-bearing region to attract an electronegative atom with available lone-pair electrons. When multiple hydrogen bonds form in an organized system, their effects can strengthen cooperatively, helping stabilize biological structures rather than acting as isolated interactions.
Hydrogen bonding responds to changes in the surrounding chemical environment. Temperature, pH, and solvent composition can alter whether individual interactions remain intact, causing them to form or break as conditions change. In biological systems, these shifts can influence the stability and organization of DNA, proteins, carbohydrates, and other molecules that depend on hydrogen-bond networks.
Individual hydrogen bonds can combine into cooperative networks, so their collective influence may exceed the effect of one contact. This cooperation helps maintain three-dimensional molecular structures and organized interactions between biological molecules. It also allows changes at one set of bonding sites or in the surrounding environment to affect broader molecular stability and organization.
In DNA, hydrogen bonds link complementary base pairs, helping hold the paired strands in an organized structure. The bonds provide stabilizing contacts while preserving the specific matching pattern between bases. Because these interactions can respond to changing conditions, their stability contributes to how DNA maintains its structure within different biochemical environments.
Hydrogen bonding helps maintain the three-dimensional structures of proteins and carbohydrates by stabilizing interactions among their molecular features. The resulting organization supports the shapes needed for these biomolecules to function and interact. Changes in temperature, pH, or solvent composition can disrupt relevant bonds, potentially altering the structural arrangement of the molecules.
Hydrogen bonding gives water distinctive properties, including cohesion and solvent behavior, which influence how biological molecules are organized in aqueous environments. The same interactions contribute to molecular recognition, allowing biomolecules to associate through chemically compatible sites. Consequently, hydrogen bonding connects water behavior with biochemical reactions and the organization of living systems.