Intermolecular Interaction between Chemical Species

Intermolecular interaction between chemical species

• Between WHAT

• Due to interactions between WHAT regions of different WHAT

Intermolecular interaction between chemical species

• Between MOLECULES

• Due to interactions between OPPOSING regions of different POLARITY (𝛿+ , 𝛿- , 𝑏𝑜𝑛𝑑 𝑑𝑖𝑝𝑜𝑙𝑒, 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑑𝑖𝑝𝑜𝑙𝑒)

INTRAmolecular interactions in chemical bonds WHAT one molecules WHAT interaction

INTRAmolecular interactions in chemical bonds WITHIN one molecules STRONG interaction

Two polar species at an infinite distance from one another have WHAT of attraction

Two polar species at an infinite distance from one another have ZERO ENERGY of attraction

TRUE Non-polar species:

• Although true non-polar species (e.g., hexane, H2) with uniform electron density where 𝛿- , 𝛿+ not assigned, due to inherent movement of electron , WHAT regions of polarity exist

TRUE Non-polar species:

• Although true non-polar species (e.g., hexane, H2) with uniform electron density where 𝛿- , 𝛿+ not assigned, due to inherent movement of electron , TEMPORARY regions of polarity exists.

Non-polar species with significant bond dipoles/Polar species/ions:

• Regions of WHAT polarity

• Movement of WHAT also present

Non-polar species with significant bond dipoles/Polar species/ions:

• Regions of PERMANENT polarity

• Movement of ELECTRONS also present

Regions of permanent polarity are due to:

• WHAT

• WHAT

• WHAT

Regions of permanent polarity are due to:

• Differing electronegativity

• Regions of larger numbers of electrons

• Formal charges

Intermolecular interactions between chemical species

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

Intermolecular interactions between chemical species

• Ion-Dipole

• Dipole-Dipole

• Hydrogen bonding

• Dipole-induces Dipole

• Induced Dipole-Induced Dipole London Dispersion Forces (LDF)

Ion-dipole

Dipole-Dipole

• Between WHAT species

• Due to WHAT regions of polarity

• WHAT attracted to WHAT

• 𝛿- (high 𝑒 density) WHAT each other

• 𝛿+ (low 𝑒 density) WHAT each other

Dipole-Dipole

• Between POLAR species

• Due to PERMANENT regions of polarity

• 𝛿- attracted to 𝛿+

• 𝛿- (high 𝑒 density) REPELLING each other

• 𝛿+ (low 𝑒 density) REPELLING each other

Hydrogen bonding

• Extreme form of WHAT

• H” bonded to a very WHAT atom

o N, O, F in NH3, H2O, HF

• Interaction between “WHAT on these molecules” and “a WHAT” on another molecule

• “electronegative atom – H – lone electron pair” MUST be in WHAT

Hydrogen bonding

• Extreme form of DIPOLE-DIPOLE

• “H” bonded to a very ELECTRONEGATIVE atom

o N, O, F in NH3, H2O, HF

• Interaction between “H on these molecules” and “a lone electron pair” on another molecule

• “electronegative atom – H – lone electron pair” MUST be in LINE

Dipole-induced dipole

• Between WHAT and WHAT species

• In mixture: as polar molecule approaching non- polar molecule, the electron cloud distorted, inducing WHAT dipole (i.e., WHAT dipole inducing WHAT dipole)

Dipole-induced dipole

• Between POLAR and NON-POLAR species

• In mixture: as polar molecule approaching non- polar molecule, the electron cloud distorted, inducing TEMPORARY dipole (i.e., PERMENANT dipole inducing TEMPORARY dipole)

Dipole-induced dipole

• In pure species: As WHAT region approaches the WHAT region of the SAME molecule

Dipole-induced dipole

• In pure species: As POLAR region approaches the NON-POLAR region of the SAME molecule

Induced Dipole-Induced Dipole London Dispersion Force (LDF)

• Between WHAT species

• Due to WHAT regions of polarity

• Two non-polar molecules approaching each other can WHAT and have their electron cloud distorted to give WHAT dipoles

Induced Dipole-Induced Dipole London Dispersion Force (LDF)

• Between NON-POLAR species

• Due to TEMPORARY regions of polarity

• Two non-polar molecules approaching each other can POLARIZE and have their electron cloud distorted to give TEMPORARY dipoles