The long hydrocarbon molecules that make up olive oil only possess weak London dispersion forces between them, yet olive oil is a viscous liquid. How is this possible? London dispersion forces are strong when molecules contain only C and H atoms. The regular, repeating shape of hydrocarbon molecules allows them to pack in a crystal structure. Hydrocarbons are more volatile than compounds that contain other kinds of atoms. The size of the molecules allows for the formation of many weak attractions with other molecules.
The London Dispersion Force is an intermolecular force, but it is a very intermolecular force. The London Dispersion, is a temporary form of attraction force, as it takes pace when the two adjacent atoms take up a position, which make the atoms form temporary dipoles. The temporary nature of the dipoles result into the weaker forms of the attraction force. The London Dispersion, is the reason for the substances to get condensed and get shaped into liquid. Further the elements or the substance can get changed into solid state with the changes in the temperature. This force is also called an induced dipole attraction, because of the loose force attracting the atoms and the molecules. They are a part of the Van der Waals Forces, which refers to the short ranged, and weak electrostatic force, present between the unchanged molecules, and it is basically generated from or arisen from the interaction between the permanent or impermanent electric dipole moments.
Since the electrons are dynamic in nature, therefore, because of their constant motion, the atoms or the molecules develop an instant attraction among theme, and there is a dipole created between the electrons, when the electrons are unsymmetrically distributed about the nucleus. Now, because of the presence of this electrostatic force or this dipole attraction in the first molecule, a second set of atom or molecules can be distorted, as the electrons are repelled by each other. Therefore it can be said that there is always a dispersion force between two electrons or two any molecules, when they are in a position where they are almost touching each other.
However, the sizes and the shapes of the molecules are two important factors for the creation of the electrostatic force or for the creation of the dispersion force. However, before this, it is important to understand that the London Dispersion forces are tended to be, stronger in nature when the molecules are polarized, and weaker when the molecules are not easily polarized. Therefore, this proves that the Polarizability of the molecules are one of the most important factor for the London Dispersion.
Now, it had already been that the sizes of the molecules are important to determine the dispersion force, since,
Firstly, the in case of the larger atom or molecule, the valence of the electrons are much further from the nuclei, than in case of a smaller molecule. Therefore, the large molecules are less tightly held with each other, which forms within the, the tendency to form a temporary dipoles.
Secondly, the larger and the heavier molecules or atoms, evince a stronger dispersion workforces, than the smaller or the lighter atoms or molecules.
Now, since the larger and the heavier elements or molecules or atoms are more likely to get dispersed because of their larger size and their heaviness. It determines the dynamic nature of the atoms or the molecules, therefore, the tendency of the larger and the heavier elements to respond dynamic to the external filed is a because of the polarizability nature present among these molecules or atoms. The polarizability is an isotropic media which can be defined by the dipole moment of the molecule or the atom, to the electric filed or the external filed that is the prime reason for the creation of the dipole moment. Therefore, the sizes of the molecules or the atoms are determined by the polarizability of the same which then influences upon the dynamic response of the atoms and the molecules to the London Dispersion forces.
Similarly, the shapes of the molecules are also very important. For example, the neo- pentane, (C5H12) is a gas while, n- pentane (C5H12) is a liquid. Therefore, the molecules of n- pentane are stronger than the neo- pentane, which is in the gaseous state, and thus, the shape or the structure of an atom or a molecule can influence upon the London Dispersion as shown or exhibited by the molecules. Also the cylindrical shape of the element is also an influence upon the polarizability of the same. Therefore, the shapes of the molecules influence the dynamic nature and the polarizability and therefore, the electrostatic force or the London Dispersion of the elements.
Now, considering the formation of Olive Oil, it had been previously mentioned that the London Dispersion is a type of Van Der Waals Force, where the interaction between the elements or the molecules are weak. However, these elements or such a nature is only found among the hydro carbon atoms or among the hydrogen or the carbon elements. Now, the dipole interactions take place especially among the hydrogen bonded elements. The dipole bonding are determined by the Columbic attractions, and the hydrogen binds are strong enough to take part in that. The hydrogen bonding is created essentially because of the dipole nature of the electronegativity difference, therefore, there is an intermolecular force which can easily make an element liquid in the room temperature. However, considering the formation of Olive Oil, it can be seen that it is a fatty acid, and the formula is, CH3 (CH2) nCOOH. Therefore, it is also an element of hydrocarbon, but the Olive Oil is a Triacylglycerol, therefore, it is bonded with the Triglyceride bond. Now in case of the normal fatty acids which are bonded with the hydrogen bond are termed as the Free Fatty Acid, but the Triglyceride bonds are much stronger. Therefore, the fatty acids are not called the free fatty acids, and the bond is stronger, therefore, the Olive Oil is not liquid, but it is a viscous liquid.
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