Posted in: zjnq.com Date: March 9th, 2010
I am doing a review for science.A polar molecule has a positive and negative end because of electronegativity. H2O, for example, is a polar molecule because 1) it has lone pairs 2) the oxygen is pulling the electrons from the hydrogen into its vicinity making it have a slightly negative charge while the two hydrogens have a slightly positive charge.A molecule is composed of one or more chemical bonds (covalent bonds) between molecular orbitals of different atoms. A molecule may be polar either as a result of polar bonds due differences in electronegativity as described above, or as a result of an asymmetric arrangement of non-polar covalent bonds and non-bonding pairs of electrons known as a full molecular orbital.
Example 1. The hydrogen fluoride, HF, molecule is polar by virtue of polar covalent bonds - in the colvalent bond electrons are displaced towards the more electronegative fluorine atom.
Example 2. In the ammonia, NH3, molecule the three N-H bonds have only a slight polarity (towards the more electronegative nitrogen atom). However, the molecule has two lone electrons in an orbital, that points towards the fourth apex of the approximate tetrahedron, (VSEPR). This orbital is not available for covalent bonding, it is electron rich which results in a powerful dipole across the whole ammonia molecule.
A polar molecule forms when an atom of high electronegativity (one that attracts electrons), such as chlorine, bonds with a less electronegative atom#If you have any other info about this subject , Please add it free.# |
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