Intermolecular forces

$Ion-Ion$ Interaction: electrostatic forces and lattice energy relation to properties

$Electrostatic force$: ^^opposite charges attract, proportional to charge between the two, and inversely related to the distance^^

==F= kq1q2/r^2==

$Lattice Energy$ - ^^the energy change upon formation of one mole of a crystalline ionic compound from its^^ ==constituent ions, proportional to magnitude of charges and inversely related to distance==

==LE= kq1q2/r==

Boiling/Melting point proportional to charges

Charge increases → electrostatic force increases

Size increases → electrostatic force decrease

$Ion-Dipole Interaction:$ ^^electrostatic interaction of ion and dipole^^

%%EX: Na+ ion and H2O (dipole) oxygen is attracted to Na+ because of lack of stability%%

%%EX: Cl- and H2O Hydrogen and Cl attracted%%

• %%so NaCl dissolves in H2O because of this b/c O surrounds Na+ and H surrounds Cl-%%

$Dipole:$ ^^one side positive and other negative; two poles of charge; polar molecule^^

==→ more electronegative atom pulls electrons towards itself==

$Permanent Dipole:$ ^^polar^^

$Dipole-Dipole Interaction$- ^^between two dipoles opposites attracts^^

• %%between C3x-O ---- C3x-O%%

==-usually between two polar molecules==

$Hydrogen Bond Interaction$ - ^^intERmolecular force between H- and N,O, or F^^

==polar covalent- shared unequally (intramolecular force)==

==covalent- shared equally (intramolecular force)==

• %%interaction between O in H2O(1) and H in H2O (2)%%

-another dipole-dipole interaction

$London Dispersion Force (Van Der Waals Force):$ ^^electron clouds distorted so one side is negative and one is positive which may lead to other atoms causing a momentary dipole force^^

-temporary induced dipole

-significant only in nonpolar force

-very weak dipole interaction

 Induced Dipole: when one dipole force causes another atom to exert dipole forces

Strength of Molecular Forces: Ion-Ion>Ion-Dipole>H-bond>dipole-dipole> LDF