Intermolecular Force Handout

Intermolecular Force Handout - the positive end of one...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 102A A Guide to Intermolecular Forces Force Description Relative Strength* Typical Occurrence Dispersion (Lon- don) attractive force from instantaneous dipole– induced dipole interac- tions very weak (ca. 0.3–5 kJ/mol) Occurs in all molecules. Important in cases of monoatomic gases (He, Ar, etc.) and non-polar mole- cules (H 2 , N 2 , CCl 4 , etc.) Dipole–induced di- pole attractive force between a molecule with a per- manent dipole and one with an induced dipole very weak Occurs in mixtures of polar gases (HCl, HBr, etc.) with monoatomic gases (He, Ar, etc.) and non-polar dia- tomic gases (H 2 , N 2 , etc.), and in solutions of polar compounds in nonpolar solvents (e.g., HCl in ben- zene) Ion–induced dipole attractive force between an ion and a molecule with an induced dipole weak Only important for solu- tions of ionic compounds in nonpolar solvents (e.g., LiCl in pyridine) Dipole–dipole attractive forces result- ing from the tendency of polar molecules to align themselves so that
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: the positive end of one molecule is near the negative end of another moderately strong (ca. 10 kJ/mol) Important for mixtures of polar gases (HCl, HBr, etc.) with each other, in liquefied polar gases, and in solu-tions of polar molecules in polar solvents (H 2 O, NH 3 ) Hydrogen bond attractive forces that exists between a hydro-gen atom covalently bound to a very electro-negative atom, X , and a lone pair of electrons on another atom Y . moderately strong (ca. 5–40 kJ/mol) Important when X is F, O, or N. Responsible for the high boiling points of H 2 O, NH 3 . Can exist in the gas, liquid and solid phases of matter. Ion-dipole attractive forces be-tween an ion and a molecule with a perma-nent dipole strong Important in cases of solu-tions of ionic compounds in polar solvents (e.g., NaCl in H 2 O, where [Na(OH 2 ) x ] + is found) *Compare these to the strength of the H–H bond in H 2 (432 kJ/mol)...
View Full Document

This note was uploaded on 03/17/2010 for the course CHEM chem102 taught by Professor Adamlist during the Spring '10 term at Vanderbilt.

Ask a homework question - tutors are online