Intermolecular Forces of Attraction (IMFA)

CONSIST OF THE SHARED PAIRS OF UNEQUAL SHARE OF ELECTRONS BY TWO ELECTRONS ATOMS TRANSFER OF EQUAL SHARE OF VALENCE ELECTRONS ELECTRON(S) BETWEEN ATOMS.  Prepared by Manie Rose E. Tapao  Describe the general types of intermolecular forces; and Specify the type of in...

CONSIST OF THE SHARED PAIRS OF UNEQUAL SHARE OF ELECTRONS BY TWO ELECTRONS ATOMS TRANSFER OF EQUAL SHARE OF VALENCE ELECTRONS ELECTRON(S) BETWEEN ATOMS.  Prepared by Manie Rose E. Tapao  Describe the general types of intermolecular forces; and Specify the type of intermolecular forces given the properties of substance.  Intermolecular forces act between molecules. In contrast, intramolecular forces are the attractive and repulsive forces within molecules that are responsible for chemical bonds and molecular structure.  London dispersion forces (LDF) Dipole-dipole interactions Hydrogen bonding Ion-Dipole  Van der Waals forces include attraction and repulsions between atoms, molecules, and surfaces, as well as other intermolecular forces. Van der Waals forces is a general term used to define the attraction of intermolecular forces between molecules. There are two kinds of Van der Waals forces: weak London Dispersion Forces and stronger dipole-dipole forces.  named after the German physicist Fritz London All atoms and molecules possess it The electron in the molecule are in constant motion and at one instant more of them may be located at one end of the molecule making that end more negative than the other end, forming what is called an instantaneous dipole.  Intermolecular forces exist between all atoms and molecules. Solely for nonpolar compounds, and noble gas Weakest attractive forces that are formed due to the temporary dipoles induced due to constant movement This force is also called induced-dipole-induced-dipole attraction  Occurs between polar covalent molecules. A polar molecule has a partial positive charge, and a partial negative charged the other, forming a dipole (having two electrically charged poles). The partial positive charge on one molecules is attracted to the partial negative charge on another molecule  The more electronegative atom becomes partially negative and has the most electron density. The least electronegative atom becomes partially positive and has a lesser electron density.  A special type of dipole- dipole interaction Results when a hydrogen atom bonded with a highly electronegative atom like nitrogen, oxygen, or fluorine Have higher boiling points due to special stability provided by the hydrogen bonds.  results from the attraction between either a cation (+) or an anion (-) with permanent polar molecules. The ions will be attracted to the opposite charges present in the dipole resulting in this type of attraction.  Example: NaCl dissolved in water (H2O): NaCl will dissociate into sodium cations (Na+) and Chlorine anions (Cl-) Because water is a polar molecule and has a partial negative and partial positive poles, the Na+ will form ion-dipole interaction with a partial negative part of the water molecule (O) , while Cl- will form an ion-dipole interaction with partial positive part of the water molecule (H+)  Types of Intermolecular Forces of Attraction (IMFA) Type of IMFA Description and Strength Examples Ion-dipole Occurs between ions (cation and NaCl dissolved in H2O; anion) and polar molecules; Ca2+ and PCl3 strongest Hydrogen bonding Hydrogen atom is attracted to N, H2O, NH3, CH3OH F, or O from another molecule; strong Dipole –dipole Polar molecules attract each CH3F and H2S; HCl other; strength increases with increasing polarity London forces Occurs between all molecules; CH4 with itself, Br2 with weakest but increases with itself increasing molecular weight  Melting and Boiling Point Viscosity Surface Tension Capillary Action Solubility  – the stronger the intermolecular forces, the higher the melting point – the measure of how well substances flow – the tendency of fluid surfaces to shrink into the minimum surface area possible – the ability of a liquid to flow against gravity up a narrow tube – the ability of a solute, to dissolve in a solvent  Devices placed inside or on the surface of the body should be durable and carefully designed to not: Cause infections Trigger allergic reactions Fail to do their function  Usually designed to be insoluble and unreactive to the cell components and body fluid Some metal implants are produced as alloys to provide strength and better compatibility May be held together by Vander Waals, Hydrogen Bonds or Covalent Bonds  Materials used for exercises and sports activities Must be durable to increase sports efficiency and effectiveness of athletes and to minimize possible injuries.  Utilizes dipole-induced dipole interaction Uses metals like copper, nickel, chromium and aluminum to produce resistors and capacitors.  Must possess durability, strength, hardness, and other important properties  Water Food coloring (3) 3 clear cups or glasses Tissue paper Ruler