* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Oxidation Number Rules
Document related concepts
Chemistry 1211 Rules for Establishing Oxidation Numbers 1. Any uncombined atom, or any atom in a molecule of an element, is assigned an oxidation number of zero. Examples: N2, Cl2, C, Sn, S8 2. The oxidation number of a simple, monatomic ion is the same as the charge on the ion. Examples: Na+ is +1, Cu+2 is +2, Cu+ is +1, F¯ is -1. 3. The oxidation numbers of some common atoms are: a. Fluorine, the most electronegative element, is -1 in all fluorine containing compounds. b. In most oxygen containing compounds oxygen is -2. In peroxides (i.e. H2O2) each oxygen has an oxidation number of -1. In the compound OF2, the oxygen atom has an oxidation number of +2. c. Hydrogen usually has an oxidation number of +1 except in metallic hydrides where it then has an oxidation number of -1 Examples: HCl, hydrogen is +1; NaH, hydrogen is -1. d. The halogens, unless bonded to an element with a higher electronegativity, have an oxidation number of -1. Examples: NaCl, chlorine is -1; HClO4, chlorine is +7. 4. Since chemical compounds are neutral, it stands to reason that the algebraic sum of their oxidation numbers must equal zero. Examples: NaCl, sodium is +1, chlorine is -1, total is 0 CO2, carbon is +4, oxygen is -2 (so -4 for two), total is 0. 5. The sum of the oxidation numbers of atoms comprising a polyatomic ion equals the charge on the ionic group. Examples: SO4-2, sulfur is +6, oxygen is -2 (so -8 for four), total is -2. NH4+, nitrogen is -3, hydrogen is +1 (so +4 for four), total is +1.