Chromatography and Intermolecular Forces
By: Courtney
The purpose of this page is to describe the influence of intermoleculas forces on the physical and chemical properties of covalent compounds. Chromatography is a way to separate the types of forces, which change the physical properties of covalent compounds.


Types of Intermolecular Forces
These are the types of intermolecular forces and their definitions.
  • Dipole- Dipole Attraction is a force that occurs when polar atom line so their positive and negative ends are close to each other.
Picture of a Dipole-Dipole Attraction.
Picture of a Dipole-Dipole Attraction.

  • Hydrogen Bonding is form of strong dipole-dipole attraction in which atoms of high electronegative atoms are bonded by hydrogen.
Picture of a Hydrogen Bond
Picture of a Hydrogen Bond

  • London Dispersion Forces is a weak force that occurs among noble gas atoms and nonpolar molecules. This is when there is a temporary dipole-dipole attraction amongst the noble gas atoms and nonpolar molecules.
Picture of London Dispersion Forces.
Picture of London Dispersion Forces.

Physical and Chemical Properties
These are the types of properties and their definitions.
  • Physical Properties are the characteristics of a substance. During a physical change chemical bonds are not broken.
This is a picture of magnesium ribbon. This has a physical property of being shinny.
This is a picture of magnesium ribbon. This has a physical property of being shinny.

  • Chemical Properties is the ability of a substance to change into a different substance.

Influence on Physical Properties
  • Hydrogen Bonds: have a high melting point, high surface tension, high heat of vaporization and a low freezing temperature.
  • Dipole-Dipole Attraction: have high melting point, high surface tension, high heat of vaporization and a low freezing temperature.
  • London Dispersion Forces: have low melting point, low surface tension, low heat of vaporization and a high freezing temperature.

Covalent Compounds
  • Compounds in which atoms that are bonded share electrons.

Chromatography
  • Separates mixtures of compounds into individual compounds.
  • Chromatography can be used in the local community and in another form of science. It is used in forensic science to analysis material recovered at a crime scene. The types of materials that forensic scientist use chromatography to detect are: explosives and drugs. Chromatography is useful in the local community because of its ability to be used in forensic science. (Lerner Ed and Lerner Brenda 670)

Work Cited
Introductory Chemistry A Foundation by Zumdahl
http://ibchem.com/IB/ibfiles/bonding/bon_img/ice.gif
http://img.sparknotes.com/content/testprep/bookimgs/sat2/chemistry/0003/sat117002_0502.gif http://catalog.miniscience.com/Catalog/Metals/Images/Magnesium_Ribbon.jpg
Thin Layer Chromatography." World of Forensic Science. Ed. K. Lerner and Brenda Lerner. Vol. 2. Detroit: Gale, 2005. 670. Gale Virtual Reference Library. Web. 13 Nov. 2009. http://find.galegroup.com/gps/start.do?prodId=IPS&userGroupName=jeff53810.ney