Review_for_Midterm_II__revised_ - Review for Midterm II...

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Review for Midterm II Note that this is NOT a comprehensive review. You will need to go through your notes to determine what else is important for midterm II. This is just some information that I believe will help you on Midterm II. I. Oxidation states 1. Oxidation number of an element uncombined with other elements is 0. Example: N 2 oxidation state of nitrogen is 0 2. Oxidation numbers for specific elements: H +1 when in combination with other non-metals -1 when in combination with metals F always –1 Example: IF 7 I +7 (F -1 ) 7 O always -2, unless with F or in a peroxide, superoxide, or ozonide Examples: OF 2 O +2 (F -1 ) 2 O 2 2- (peroxide) (O -1 ) 2 You can figure out the oxidation state of each species in a compound based on the electronegativity of the atom in question (except for transition metals). The atom with the greater electronegativity will have the greater negative charge. Example: SeH 2 Se -2 (H +1 ) 2 Note that you do NOT have to balance a redox equation in order to assign the oxidation numbers. Also, to receive full credit, you must write the oxidation number for each atom rather than the total charge of a group of atoms [i.e. H 2 O (H +1 ) 2 O 2- not (H) 2 2+ O 2- ] II. Lewis Dot Structures 1. ALWAYS compare the electronegativity of the atoms in the compound to make sure that there will be covalent bonding in the molecule. If the difference in electronegativity between two atoms is greater than 2, then you probably will have ionic bonding ; if not, then you’ll probably have
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This note was uploaded on 04/07/2008 for the course CHEM 6A taught by Professor Pomeroy during the Winter '08 term at UCSD.

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Review_for_Midterm_II__revised_ - Review for Midterm II...

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