molecular interactions in 3D space

In this file is the description of molecular interactions, introduction, types of interactions, factors affecting them.

1. MOLECULAR INTERACTIONS IN 3D SPACE

2. Group Members Maheen Imran (L1S21BSBT0106) Sana Amir (L1S21BSBT0105) Madiha Asad (L1S21BSBT0110)

3. MAHEEN IMRAN ( L1S21BSBT0106) MOLECULAR INTERACTIONS IN 3D SPACE

4. Molecular Interactions: “Molecular interaction are attractive and repulsive forces between molecules and non bonded items.”

5. Importance Of Molecular Interactions: Protein Folding Drug Design Material Science Sensors Nano Technology Origin Of Life

6. Types Of Molecular Interactions: Intramolecular forces: Intramolecular forces are the forces that hold atoms together within a molecule. i.e.; chemical bonds such as ionic, covalent and metallic bonds. Intermolecular forces: Intermolecular forces are forces that exist between molecules. i.e.; Dipole-dipole interactions occur in HCl molecules.

7. Difference In Intermolecular And Intramolecular Intermolecular Force Intramolecular Force Intermolecular forces are the forces that hold molecules in a substance Intramolecular forces are the forces hold atom in a molecule Weaker than intramolecular force Stronger than intermolecular force Determine the state and properties of matter Determine the chemical behavior of a substance Attractive forces Chemical bonds

8. Categorization Of Forces: Intermolecular forces are categorized as: Ion dipole Dipole-dipole forces London dispersion Hydrogen bonding forces Intramolecular forces are categorized as : Covalent Ionic Metal bonds

9. Ion Dipole Forces: “An ion-dipole interaction is the intermolecular force of attraction between a charge ion (cation or anion) and a molecule.” Found in solution where ionic compounds dissolve in polar solvents.

10. Example: Na+ (sodium ion) and H2O (water molecule) Na+: a cation Partially positive end of H2O: from H atoms Partially negative end of H2O: from O atom Sodium attracts the oxygen atom of the water molecule, while it repels the hydrogen atom.

11. SANA AMIR (L1S21BSBT0105) LONDON DISPERSION FORCES

12. London Dispersion Forces: “Type of force acting between atoms and molecules that are normally electrically symmetric .” It is the weakest intermolecular force between non-polar molecules . Temporary attractive force makes it temporary dipoles

13. Why Does The Temporary Dipole Occur? Results from random movement of electrons Induced dipole The net result is that there is a stronger attractive force between molecules

14. Factors Affecting London Forces: Shape of the molecule Molecular weight Polarizability Distance between the molecules

15. Dipole-dipole Forces: “Attractive forces between the positive end of one polar molecule and the negative end of another polar molecule .” It is the electrostatic attraction between the molecules with permanent dipoles. Cause an increase in Boiling point. For example, The boiling point of HCl is 188K and that of F2 is 85 K

16. Factors Affecting Dipole-dipole Forces: Electronegativity difference Dipole moment Intermolecular distance

17. Strength Of Intermolecular Forces:

18. MADIHA ASAD (L1S21BSBT0110) HYDROGEN BONDING

19. Hydrogen bonding: “ Hydrogen bonding results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom .” Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom.

20. Types of Hydrogen Bonding: There are two types of H bonds, and it is classified as the following: Intermolecular Hydrogen Bonding water and hydrogen fluoride Intramolecular Hydrogen Bonding Salicilaldehyde and ortho – nitro phenol

21. Hydrogen bonding Strength: Hydrogen bond strengths range from 4 kJ to 50 kJ per mole of hydrogen bonds . The strength of the hydrogen bond depends on the electronegativity of the atoms H-F>H-O>H-N The hydrogen bond is a weak bond. The strength of hydrogen bond is in-between the weak van der Waals forces and the strong covalent bonds. The dissociation energy of the hydrogen bond depends upon the attraction of the shared pair of electrons and hence on the electronegativity of the atom.

22. Conditions for Hydrogen bonding: As a result of hydrogen bonding, a hydrogen atom links the two electronegative atoms simultaneously , one by a covalent bond and the other by a hydrogen bond. The conditions for hydrogen bonding are: The molecule must contain a highly electronegative atom linked to the hydrogen atom. The higher the electronegativity more is the polarization of the molecule. The size of the electronegative atom should be small. The smaller the size, the greater is the electrostatic attraction.

23. Effects of Hydrogen Bonding on Elements: Association The molecules of carboxylic acids exist as dimer because of the hydrogen bonding   (molecular masses double) Dissociation In aqueous solution, HF dissociates and gives the difluoride ion instead of fluoride ion. This is due to hydrogen bonding in HF.

24. Properties of Hydrogen Bonding: Solubility Melting and boiling point Volatility Viscosity and surface tension The lower density of ice than water

25. Hydrogen Bonding in Hydrogen fluoride: Fluorine having the highest value of electronegativity forms the strongest hydrogen bond.

26. Hydrogen Bonding in Water A water molecule contains a highly electronegative oxygen atom linked to the hydrogen atom. Oxygen atom attracts the shared pair of electrons more and this end of the molecule becomes negative whereas the hydrogen atoms become positive.

27. Hydrogen Bonding in  Ammonia: It contains highly electronegative atom nitrogen linked to hydrogen atoms.

28. Hydrogen Bonding in Alcohols and Carboxylic acid: Alcohol is a type of an organic molecule which contains an -OH group. Normally, if any molecule which contains the hydrogen atom is connected to either oxygen or nitrogen directly, then hydrogen bonding is easily formed.

29. Hydrogen Bonding in Polymers: Hydrogen bonding is an important factor in determining the 3D structures and properties that are acquired by synthetic and natural proteins.   Hydrogen bonds also play an important role in defining the structure of cellulose as well as derived polymers such as cotton or flax .

30. Hydrogen Bonding in Proteins:

31. Hydrogen Bonding in Nucleic Acid:

32. Video…… https://www.youtube.com/watch?v=XEazos-Tdoo https://www.youtube.com/watch?v=q0cH8TUBHRU