Hydrogen Bonding: Definition, Properties

Hydrogen bond

Hydrogen bonding is a connection including a hydrogen atom that is positioned among a pair of other atoms that have a high electronegativity; this type of link is relatively weak than an ionic bond or a covalent bond, yet better and powerful over van der Waals forces. Atoms in distinct molecules or different regions of the identical molecule can form hydrogen bonds with one another. In this reaction, one atom of the pair (the donor), which is usually fluorine, nitrogen, or oxygen atom, forms a covalent bond with a hydrogen atom (FH, NH, or OH), with which it shares electrons unequally; the donor’s high electron fondness causes the hydrogen to acquire a slight positive charge as a result of this bond.

Properties of Hydrogen bond

The Characteristics of Hydrogen Bonding

• Low volatility is due to the fact that the boiling temperature of compounds containing hydrogen bonds between different molecules is higher than that of unbonded compounds.
• Lower alcohols are more soluble in water than higher alcohols even though of the hydrogen bonding which can happen between the water molecule and the alcohol molecule.
• When water molecules are trapped together in solid ice, this results in a cage-like structure. Water molecules are tetrahedrally bonded to one another, and each water molecule has 4 additional water molecules as neighbors. It is not as closely packed in the solid form as it is in the liquid state because the molecules are not quite as small. Because of the melting of the ice, this case-like structure collapses, bringing the molecules even closer together. Consequently, the volume of water decreases, while the density of water increases for the same amount of liquid. As a result, ice has a relatively low density over water at 273 degrees Celsius. 
• In compounds which have a linked molecule, hydrogen bonding is present, resulting in viscosity and surface tension. Because of this, the flow of information becomes more difficult. Because of their high surface energy and viscosity, they are more viscous than most other materials.

Types of Hydrogen bond

• Intermolecular Hydrogen Bonding – Intermolecular hydrogen bonding happens whenever hydrogen bonds are established among molecules of the identical or different substances. Water, alcohol, as well as ammonia, for example, all have hydrogen bonding properties.

• Introduction to Intramolecular Hydrogen Bonding – Intramolecular hydrogen bonding is a type of hydrogen bonding that happens within a single chemical compound. Compounds with two groups are known to contain it; one of the groups contains a hydrogen atom that is linked to an electronegative atom, and the other contains an extremely electronegative hydrogen atom that is coupled to an extremely electronegative atom of the other group. The link is formed among higher electronegative atoms with one category as well as the hydrogen of all the other groups.

Examples of hydrogen bond

1.Water – The water molecule contains an oxygen atom that is extremely electronegative and is coupled to a hydrogen atom. The oxygen atoms are more strongly attracted to the pair of electrons, causing that side of the molecule to become negatively charged whereas the hydrogen atoms get positively charged.

2.Fluoride- Fluorine forms the strongest hydrogen bond because it has the highest electronegativity, resulting in the compound hydrogen fluoride.

3.Ammonia- It is made up of nitrogen atoms which are extremely electronegative and thus are connected to hydrogen atoms, thus forming a compound.

Effects of hydrogen bond

• Fluoride dissolves in water as well as releases the difluoride ion, rather than the fluoride ion, which is the result of dissociation. Because of hydrogen bonding, this happens in HF. Hydrogen bonds are not formed by the molecules of HCl, HBr, and HI. The absence of compounds such as KHCl2, KHBr2, and KHI2 reveals why they are not found.
• Carboxylic acid molecules occur as dimers as a result of hydrogen bonding. Solvent-soluble chemicals possess molecular mass that really are twice as big as those predicted by its simple formula.

Weaker form

Van der Waals forces are weak as well as covalent bonds are strong, while the intensity of the hydrogen bond is somewhere in the middle.When a hydrogen bond is broken, the disintegration energy of the bond is determined by the affinity of the pair of electrons and, consequently, by the atom’s electronegativity.Weaker hydrogen bonds have been observed between hydrogen atoms obligated to components like sulfur (S) or chlorine (Cl); sometimes carbon (C) could even act like a donor, especially regarding whenever the carbon and one of its neighbors is electronegative, as is the case in chloroform, aldehydes, and terminal acetylenes, among other compounds.

Hydrogen

A combustible gaseous material that is white, scentless, bland, and has no odor or taste, hydrogen (H) is the most basic of all chemical elements, and it is also the most abundant. The hydrogen atom has a nucleus that is composed of a proton that has each positive electrical charge and an electron which has each unit of negative electrical charge. An electron is also associated with the nucleus that has each positive electric charge.Under normal circumstances, hydrogen gas is a weak accumulation of hydrogen molecules, which are composed of a groups of atoms, a diatomic molecule, H2.In fact, the name hydrogen is extracted from Greek words that literally translate as “maker of water.”

Conclusion

In addition to being directional, H-bonds have enthalpies of formation on the order of nkT at room temperature, with n 10 for weak H-bonds. These three fundamental properties give H-bonds their previously unappreciated significance. Consequently, they perform a unique function in everyday life, albeit one that has been underappreciated in recent years. Because of their directionality, they are able to serve as the starting point for very well molecular structures, in a similar way as covalent compounds allow atoms to join and construct well-defined molecules. The enthalpies of formation of covalent bonds are one order of magnitude stronger than those of hydrogen bonds. The strong connections that hold most molecules together at ambient temperature also make them inflexible, allowing only modest frequency movements of atoms near their equilibrium locations to happen. Temperature fluctuations have little or no effect on their behavior. Assembly of molecules bound together by hydrogen bonds is stable, but it can be made more flexible and evolutive by using energy that is within the range of thermal fluctuations to modify their structure.