STEPS FOR DRAWING ELECTRON-DOT MODELS 1. Arrange the atoms of the compound or complex ion so as to show how they are linked together by chemical bonds. When in doubt, assume that the least electronegative atom is central (not an outer atom). 2. Count the valence electrons for each atom. For non-transition elements, the number of valence electrons is the same as the group number of the element. For a complex anion, add electrons equal to the negative charge. For a complex cation, subtract electrons equal to the positive charge. The total is the number of electrons to be used in generating the model. 3. Draw in single bonds (-) between all atoms that are linked together, keeping in mind that each such bond represents the use of two electrons from the total established in step 2. 4. With the remaining electrons, first add pairs (:) to all of the outer atoms to make octets (except H), then add any leftover electrons to the central atom. The octet for each atom includes pairs used to make bonds in step 3.
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This note was uploaded on 03/01/2012 for the course CHEM 116 taught by Professor Robertcarter during the Spring '07 term at University of Massachusetts Boston.