ChemWiki

username password

Linear Molecular Geometry

    AX2E3 AX2E3
    Shape: Linear
      Steric Number: 5
      Lone Pairs: 3
      Polar/NonPolar: NonPolar
      Hybridization: sp3d
      Example: I3-

    NOTES: This molecule is made up of 5 sp3d hybrid orbitals. Three orbitals are arranged around the equator of the molecule with bond angles of 120o. Two orbitals are arranged along the vertical axis at 90o from the equatorial orbitals. The shape of the orbitals is trigonal bipyramidal. All three equatorial orbitals contain lone pairs of electrons. The three atom molecule has a linear shape.

    Beryllium Hydride

    An example of linear electron pair and molecular geometry is BeH2. This molecule is electron deficient and does not follow the octet rule because it has only 4 valence electrons. The hydrogen atoms are as far apart as possible if opposite each other at 180o; this is linear geometry.

    Beryllium hydride is a solid at room temperature. It does not have any common uses and all beryllium compounds are quite toxic.

    202beh2mg.gif

    Carbon Dioxide

    In this example, CO2, the Lewis diagram shows carbon at the center with no lone electron pairs. The carbon and and both oxygen are bonded through double bonds which counts as "two electron pairs". Hence the molecule has two electron pairs and is linear. Carbon dioxide is the major product of all combustion reactions involving carbon based materials such as natural gas, gasoline, and coal. Carbon dioxide is the end product of animal/human metabolism/respiration. It is also the gas that provides the carbonation in soda and beer. Carbon dioxide is the major gas implicated in the greenhouse effect or global warming. The gas in the atmosphere acts to trap heat that might otherwise escape from the earth to outer space.

    202co2.gif

    Hydrogen Cyanide

    In this example, HCN, the Lewis diagram shows carbon at the center with no lone electron pairs. The carbon and nitrogen are bonded through a triple bond which counts as "one electron pair". Hence the molecule has two electron pairs and is linear. Chime in new window

    Hydrogen cyanide is prepared on an industrial scale by the reaction of methane with ammonia in the presence of a platinum catalyst at 1200oC. It boils at 25oC, and thus is a gas a room temperature. HCN is very toxic and will cause death in a matter of minutes if inhaled or ingested.

    202hcn.gif

    Contributors

    This page viewed 17360 times
    The ChemWiki has 9230 Modules.

     

    Creative Commons 
License    UC Davis ChemWiki by University of California, Davis is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License
    Permissions beyond the scope of this license may be available at copyright@ucdavis.edu. Terms of Use
    Powered by Mindtouch Core 2010

    You must login to post a comment.
    FileSizeDateAttached by 
     202beh2mg.gif
    No description
    6.03 kB18:18, 23 Aug 2009dlarsenActions
     202co2.gif
    No description
    8.13 kB18:18, 23 Aug 2009dlarsenActions
     202hcn.gif
    No description
    7.58 kB18:18, 23 Aug 2009dlarsenActions