INTERMOLECULAR FORCESAmneet Sihota, Crystal Johnsa, Gabriel Wach, Jacob Wells

DIPOLE-DIPOLE FORCES

Description: forces between positive and negative ends of two polar molecules.

Types of Molecules: Positive and negative polar molecules (Permanent net dipoles)

Relative Strength: From 5 to 20 kJ per mole Effect on Properties: Large dipole movements

create solids Real Life Example: Water, Hydrochloric Acid Other Important effects: Partial charge bonds

it together.

HYDROGEN BONDING

Description: Electromagnetic attractive interaction of a polar hydrogen atom in a molecule/chemical & electronegative atom from another molecule/chemical.

Types of Molecules: Hydrogen atom and either oxygen, fluorine, or nitrogen.

Relative strength: 5x stronger than dipole-dipole.

Effect on properties: Causes a high boiling point

Real-life example: H2O sticking to clothes Other important facts: Partly responsible in

the formation of proteins and amino acids.

DISPERSION

Description: A very weak attraction force acting between partials of matter

Types: Exist in all molecules especially non-polar

Relative Strength: The weakest force Effects on properties: Liquefied can cause a

non polar autumns’ or molecules to condense into liquids and solids as the temperatures lowers.

Important Facts : LDF – London Dispersion force causes non- polar substances to condense to liquids & freeze into solids.

ION DIPOLE Description: an attractive force that results from

electrostatic attraction between an ion and a neutral molecule that has a dipole.

Types: Polar Molecules Relative Strength: Weak compared to intramolecular

forces but stronger than hydrogen bonds. Effects on properties: Cations attract the partially

negative or neutral end of a polar molecule. Anions attract the partially positive or neutral end of a polar molecule

Important Facts : Ion-Dipole attractions become stronger as either the charge on the ion increases, or as the magnitude of the dipole of the polar molecule increases.

BIBLIOGRAPHY

1. Handbook of Nanostructured Materials and Nanotechnology; Nalwa, H.S., Ed.; Academic Press: New York, NY, USA, 2000; Volume 5, pp. 501-575

2.http://www.elmhurst.edu/~chm/vchembook/161Ahydrogenbond.html

3.http://www.chem.purdue.edu/gchelp/liquids/dipdip.html

4.http://www.chem.purdue.edu/gchelp/liquids/iondip.html