Dipole-dipole forces are present between the molecules of a polar compound. For example, due to the difference of electro negativity, values of the bonded atoms; the molecule of the hydrogen chloride becomes a polar molecule. Its chlorine end is called negative region and the hydrogen region is called positive region. Due to these poles, the molecules of hydrogen chloride attract each other. These forces of attraction are called dipole-dipole forces. As a result of these attractive forces, both the melting and boiling point of these polar compounds are increased.
Usually the dipole-dipole forces between the water molecules are quite weak and thus have little effect on the physical properties of these molecules. In some cases, however, these forces become strong enough and have large affect on the physical properties of molecules. Water is such an example. These inter molecular forces are quite strong in water and thus its melting and boiling points are relatively higher. These strong dipole-dipole forces are given the name of hydrogen bonding.
Hydrogen bonding is present in compounds in which the hydrogen atom is bonded to anyone of the very strong electronegative atoms F, O, or N. an appreciably strong positive charge is thus developed on the hydrogen atom due to large difference in there electronegative values. As a result, a strong force of attraction is created when this positively charged hydrogen atom is attracted by F, O or N belonging to neighboring molecule. This force of attraction is called hydrogen bonding.
Usually the dipole-dipole forces between the water molecules are quite weak and thus have little effect on the physical properties of these molecules. In some cases, however, these forces become strong enough and have large affect on the physical properties of molecules. Water is such an example. These inter molecular forces are quite strong in water and thus its melting and boiling points are relatively higher. These strong dipole-dipole forces are given the name of hydrogen bonding.
Hydrogen bonding is present in compounds in which the hydrogen atom is bonded to anyone of the very strong electronegative atoms F, O, or N. an appreciably strong positive charge is thus developed on the hydrogen atom due to large difference in there electronegative values. As a result, a strong force of attraction is created when this positively charged hydrogen atom is attracted by F, O or N belonging to neighboring molecule. This force of attraction is called hydrogen bonding.