Thermodynamics: Role of Intramolecular and Intermolecular bonds

Summary

What does thermodynamics do? Thermodynamics monitors the transfer of energy between molecules. Every time a reaction takes place, the chemical bonds are broken, and they then rearrange themselves into lower energy, more stable configurations. The same process occurs when a cluster of molecules breaks bonds; the cluster of molecules breaks in a way that makes the system more entropic.

The electrostatic interaction between charges or partial charges can be summed up simply as opposite charges repel one another while the same charges attract one another. In molecules or compounds, there are two different forms of electrostatic forces: intermolecular forces, which exist between molecules as detailed below, and intramolecular forces, which exist between the linked atoms of a compound or molecule.

Intramolecular bonds hold atoms. Intermolecular bonds hold molecules. The intramolecular bonds determine the chemical properties of a molecule. The intermolecular bonds determine the physical properties of a substance.

Bonds are the storage space of energy of a substance that converts to other forms of energy. Thermodynamics simply monitors the transaction of energy.

Intramolecular bonds

Atoms combine to create compounds because doing so allows them to reach lower energies than they would otherwise. The energy released, which is typically in the form of heat, is equal to the difference between the energies of the bound and separated atoms. In other words, the energy of the bound atoms is smaller than that of the free atoms. Energy is always released when atoms come together to form a compound, and the complex itself has lower total energy. The energy released then becomes a source of energy for mechanical work.

Intermolecular bonds

Behind every thermodynamic property like boiling point, melting point, surface tension, viscosity, heat capacity, latent heat etc the intermolecular forces determine the values. ??

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Detail

Intramolecular bonds

There are mainly three types of intramolecular bonds

Metallic bonds

Covalent bonds

Ionic bonds

?Metallic bonds

Metals are made up of a large number of atoms that are grouped as +ions in a crystal lattice, a precise three-dimensional structure, with some of the outermost electrons traveling freely across the entire metal, creating the sea of electrons seen in the image. The link between the atoms in a piece of metal is created by the attraction between the +ions and the ocean of freely flowing electrons. The delocalized electrons among many properties provide thermal and electrical conductivity.

Typically, metallic bonds are the strongest chemical bonds. ?

Ionic bonds

The bonding electrons entirely transfer from a more electropositive atom to a more electronegative atom when the difference in electronegativity between the bonded atoms is high, often greater than 1.9, resulting in the formation of a cation and an anion, respectively. As seen in the image, there is an electrostatic interaction between cation and anion in which like charges attract one another and unlike charges repel one another. In a 3D crystal lattice, the cations and anions arrange themselves so that the attractive interactions are maximized and the repulsive interactions are minimized. Ionic bonds are typically stronger than other forms of bonding but weaker than metallic bonds.

?Covalent bonds

The bonding electrons are shared between the bonded atoms as shown in the image when the electronegativity difference between the bonded atoms is moderate to zero, or typically less than 1.9. Covalent bonds, which bind atoms in molecules, are held together by the attractive force between their nuclei and bonding electrons. The covalent bond typically has a lower strength than ionic and metallic bonds. Since they have no free electrons, they can conduct electricity.

Intermolecular bonds

The electrostatic interactions between molecules are what are known as intermolecular forces. The intermolecular forces have a significant influence in shaping the characteristics of compounds even though they are often much weaker than the intramolecular forces.

Types of intermolecular bonds

Dipole-dipole interaction

Hydrogen bonds, and

London dispersion forces

?Dipole-Dipole interaction

Polar molecules have a partial positive charge in one end and the other end a partial negative charge creating permanent dipoles. Although dipole-dipole interactions are weaker than ionic connections, polar molecules have electrostatic interactions with one another through their + and – ends. As seen in the image, the polar molecules are oriented to maximize the attractive interactions between the opposing charges and to minimize the repulsive forces between the same charges.

Hydrogen bonds

A hydrogen bond is a weak type of force that forms a special type of dipole-dipole intermolecular attraction when a hydrogen atom is bonded directly to one of the most electronegative elements like nitrogen (N), oxygen (O), or fluorine (F). This causes the hydrogen to acquire a significant amount of positive charge. Each of the three elements F, O, and N which form hydrogen bonds is not only significantly negative but also has at least one "active" lone pair. Lone pairs at the 2-level have the electrons contained in a relatively small volume of space which therefore has a high density of negative charge. Lone pairs at higher levels are more diffused and not so attractive to positive charges. Hydrogen bonds have about a tenth of the strength of an average covalent bond and are constantly broken and reformed in liquid water. Hydrogen bonds vary in strength.?

London dispersion forces [ van der Walls forces]

It could seem counterintuitive for the nonpolar molecules to interact with one another. In reality, all molecules, even nonpolar molecules, interact with one another through forces known as London dispersion forces. Atoms' electron clouds are not always symmetrical around their nucleus. It produces a transitory dipole by momentarily swaying to one side or the other. A dipole in the nearby is caused by the transitory dipole. Please refer to the image.

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