hydrogen bonds

Dipole-dipole forces have strengths that range from 5 kJ to 20 kJ per mole. They are much weaker than ionic or covalent bonds and have a significant effect only when the molecules involved are close together (touching or almost touching). Polar molecules have a partial negative end and a partial positive end.

There are three different types of intermolecular forces in terms of strength. They are (strongest to weakest) hydrogen bonding, dipole-dipole and Van der Waals’ forces.

HF

Hydrogen bonds are strong intermolecular forces created when a hydrogen atom bonded to an electronegative atom approaches a nearby electronegative atom. Greater electronegativity of the hydrogen bond acceptor will lead to an increase in hydrogen-bond strength.

The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.

The strength of hydrogen bond depends upon the coulumbic interaction between the electronegativity of the attached atom and hydrogen. Fluorine is the most electronegative element. F−H−−−F bond will be strongest H bond.

covalent bond

water

Intramolecular forces are stronger than intermolecular forces, because the attractions that hold compounds together are stronger than the attractions between molecules.

Hydrogen-Bonds Hydrogen bonds are a special case of dipole-dipole interactions. H-bonds are the strongest intermolecular force.

There are three types of intermolecular forces: London dispersion forces (LDF), dipole- dipole interactions, and hydrogen bonding.

There are five types of intermolecular forces: ion-dipole forces, ion-induced-dipole forces, dipole-dipole forces, dipole-induced dipole forces and induced dipole forces. Ion-dipole forces exist between ions and polar (dipole) molecules.

The three major types of intermolecular interactions are dipole–dipole interactions, London dispersion forces (these two are often referred to collectively as van der Waals forces), and hydrogen bonds.

Ion-ion forces (attraction between two ions) are the strongest interactions overall. Hydrogen bonding, an attraction between a hydrogen atom and a highly electronegative atom like fluorine, oxygen, or nitrogen, is the second strongest interaction listed.

ammonia

two types

Hydrogen bonding can occur between two atoms of same molecule or between two atoms of different molecule. Depending on that hydrogen bonding are of two types: Intermolecular hydrogen bonding. Intramolecular hydrogen bonding.

Hydrogen bonds are weak, noncovalent interactions, but the large number of hydrogen bonds between complementary base pairs in a DNA double helix combine to provide great stability for the structure.

Although NH3 vigorously accepts hydrogen bonds in the gas phase, there is yet no example in which NH3 acts as a hydrogen-bond donor. NH3 accepts hydrogen bonds in the complexes H3N-HCN (9), H3N-HF (10), H3N-HOH (11), H3N-HCI (12), H3N-HBr (13), H3N-HCCH (14), H3N-HCF3 (15), and H3N-HSH (16).

Nitrogen is highly electronegative as compared to phosphorus. This causes a greater attraction of electrons towards nitrogen in NH 3 than towards phosphorus in PH 3. Hence, the extent of hydrogen bonding in PH 3 is very less as compared to NH 3.

Why Hydrogen Bonds Form The reason hydrogen bonding occurs is because the electron is not shared evenly between a hydrogen atom and a negatively charged atom. The result is that the hydrogen atom carries a weak positive charge, so it remains attracted to atoms that still carry a negative charge.

Ammonia (NH3) has polar covalent bond.