Which of the Following Molecules Can Hydrogen Bond to Another Molecule of Itself?

Learning Objectives

• Define hydrogen bond.
• Depict molecular structures that will participate in hydrogen bond formation.

What's the divergence between these two molecules?

A rough rule of thumb is that higher molecular-weight materials have college boiling points than their lower molecular weight counterparts.  More free energy is needed to move the larger molecule from the liquid state to the vapor state.  However, ammonia has a boiling point of -33.34°C and a molecular weight of 17 while nitrogen (molecular weight 28) has a boiling point of -195.8°C.  The lighter ammonia molecule must have other factors that influence its physical properties.

Hydrogen Bonding

The bonny force between water molecules is a dipole interaction.  The hydrogen atoms are leap to the highly electronegative oxygen atom (which as well possesses 2 lone pair sets of electrons, making for a very polar bond.  The partially positive hydrogen atom of one molecule is then attracted to the oxygen atom of a nearby water molecule (see Figure below ).

Figure ane. A hydrogen bond in water occurs betwixt the hydrogen atom of one water molecule and the lone pair of electrons on an oxygen atom of a neighboring water molecule.

A hydrogen bond is an intermolecular attractive strength in which a hydrogen atom that is covalently bonded to a small, highly electronegative atom is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole interactions.  The forcefulness of a typical hydrogen bond is near five% of that of a covalent bond.

Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to 1 of three elements: fluorine, oxygen, or nitrogen.  These three elements are so electronegative that they withdraw the majority of the electron density in the covalent bond with hydrogen, leaving the H cantlet very electron-deficient.  The H atom nearly acts equally a bare proton, leaving information technology very attracted to lone pair electrons on a nearby atom.

The hydrogen bonding that occurs in water leads to some unusual, only very important properties.  Nearly molecular compounds that have a mass similar to water are gases at room temperature.  Considering of the stiff hydrogen bonds, water molecules are able to stay condensed in the liquid state.  The figurebelow shows how the aptitude shape and 2 hydrogen atoms per molecule allows each water molecule to be able to hydrogen bond to 2 other molecules.

Effigy 2. Multiple hydrogen bonds occur simultaneously in water because of its bent shape and the presence of two hydrogen atoms per molecule.

In the liquid country, the hydrogen bonds of water can break and reform as the molecules flow from one identify to another.  When h2o is cooled, the molecules begin to irksome downwardly.  Eventually, when water is frozen to water ice, the hydrogen bonds become permanent and grade a very specific network.

Figure three. When water freezes to ice, the hydrogen bonding network becomes permanent. Each oxygen atom has an approximately tetrahedral geometry – ii covalent bonds and 2 hydrogen bonds.

The bent shape of the molecules leads to gaps in the hydrogen bonding network of ice.  Ice has the very unusual property that its solid state is less dense than its liquid state.  Water ice floats in liquid water.  Virtually all other substances are denser in the solid land than in the liquid country.  Hydrogen bonds play a very important biological role in the physical structures of proteins and nucleic acids.

Summary

• Hydrogen bonds form when a H attached to a Due north, O, or F cantlet interacts with another N, O, or F atom.

Exercise

Use the link below to answer the following questions:

http://www.elmhurst.edu/~chm/vchembook/161Ahydrogenbond.html

1. What are the features of Northward and O that crusade and so to form H bonds with H?
2. Will all H atoms course H-bonds?
3. What is the length of an H-bond compared to the length of a covalent bond?

Review

1. How stiff is a hydrogen bail?
2. What happens when H is covalently bonded to North, O, or F?
3. How does the shape of the water molecule touch on its properties?

Glossary

• hydrogen bond: An intermolecular bonny force in which a hydrogen cantlet that is covalently bonded to a small, highly electronegative atom is attracted to a alone pair of electrons on an cantlet in a neighboring molecule.

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Source: https://courses.lumenlearning.com/cheminter/chapter/hydrogen-bonding/