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RULES OF OXIDATION NUMBER ASSIGNMENT

RULES OF OXIDATION NUMBER ASSIGNMENT . STEPS IN ASSIGNNING OXIDATION NUMBERS 1) IF THE PERIODIC TABLE GIVES ONLY ONE OXIDATION STATE, USE THAT THAT STATE. EXAMPLE Zn +2 . 2) APPLY THE RULES OF THIS POWERPOINT TO SOLVE FOR OXIDATION NUMBERS OF ELEMENTS WITH MULTIPLE OXIDATION STATES.

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RULES OF OXIDATION NUMBER ASSIGNMENT

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  1. RULES OF OXIDATION NUMBERASSIGNMENT STEPS IN ASSIGNNING OXIDATION NUMBERS 1) IF THE PERIODIC TABLE GIVES ONLY ONE OXIDATION STATE, USE THAT THAT STATE. EXAMPLE Zn+2 . 2) APPLY THE RULES OF THIS POWERPOINT TO SOLVE FOR OXIDATION NUMBERS OF ELEMENTS WITH MULTIPLE OXIDATION STATES. 3) IF A MULTIPLE OXIDATION STATE ELEMENT HAS NO RULE, ASSIGN IT A VARIABLE AND SOLVE USIMNG THE ALGEBRA RULE(SLIDE 3).

  2. THE SUM OF THE OXIDATION NUMBER (STATE ) OF EACH ATOM IN A COMPOUND EQUALS THE CHARGE OF THAT COMPOUND.KMnO4 GIVEN: K IS +1(GROUP 1 RULE ), O IS -2 (OXYGEN RULE)Mn HAS MULTIPLE STATES(PERIODIC TABLE)+1 + X + 4(-2) = 0 ALGEBRA RULE EXAMPLES. Use group one to find other elements. note: caution with oxygen in binary compounds Li2O2 2(+1) +2(X) = 0 X=O (oxygen) = -1 Use group one as a known for muli oxidation stare elements Na2SO4 2(+1) + (X) + 4(-2)= 0 X = S = +4 each S

  3. GROUP ONE ELEMENTS ARE ALWAYS 1+ IN COMPOUNDS OR AS FREE (AQ) IONS.Ex in NaClEACH Na has an oxidation state of 1+. in K2SO4 EACH K has an oxidation state of 1+. A Li+1 (aq) free ion has an oxidation number of 1+. Na2SO4 2(+1) + (X) + 4(-2)= 0 X = S = +4 each S Use group one to find other elements. Li2O2 2(+1) +2(X) = 0 X=O (oxygen) = -1 each GROUP ONE RULE EXAMPLES. Use group one as a known for muli oxidation stare elements.

  4. GROUP TWO ELEMENTS HAVE AN OXIDATION STATE OF 2+ IN COMPOUNDS AND AS FREE (AQ) IONS.Ex in1) BaCl2 EACH Ba has an oxidation state of 2+ JJIBGO 2) In Ca3(PO4)2 EACH Ca has an oxidation state of 2+. A free Mg+2 ION (AQ) has an oxidation state of 2+. Use group TWO to find other elements. BaO2 1(+2) +2(X) = 0 X=O (oxygen) = -1 each GROUP ONE RULE EXAMPLES. Use group TWO as a known for muli oxidation stare elements. Ca3(PO4)2 3(+2) + 2(x) + 8(-2)=0 X = P = +6 each P

  5. ALL UNCOMBINED NEUTRAL (ELEMENTAL STATE) ATOMS HAVE AN OXIDATION STATE OF 0. THE NONPOLAR COVALENT DIATOMOIC MOLECULES OF THE PERIODIC TABLE ALSO HAVE AN OX# OF 0.EX: Au0, Fe0, Na0, etc.EX: H2, O2, N2, Cl2, Br2, I2, F2 are3 all in the 0 oxidation state

  6. THE OXIDATION NUMBER OF IONS IS THE IONIC CHARGE.EX: Au+2 = 2+, Fe+3 = 3+, Na+ = 1+, etc.EX: NO3- HAS AN OXIDATION NUMBER OF 1- FOR THE (EACH) POLY ATOMIC ION GROUP.

  7. USE CAUTION IN BINARY COMPOUNDS OF OXYGEN AND HYDROGEN -- CHECK FOR RULE EXCEPTIONS. THE OXYGEN RULES: Eachoxygen USUALLY has an oxidation state of 2- in compounds, 0 in O2. EX, in H2O oxygen is 2- In H2SO4 EACH oxygen is 2- IMP -- EXCEPTION #1– when oxygen is contained in a PEROXIDE, it has an oxidation state of 1-.PEROXIDES - contain the peroxide ion (O2-2), EACH oxygen is 1-.- peroxides are when 2 group one elements combine with the peroxide ionH2O2, Li2O2, K2O2 are peroxides, each O is 1-BaO2, CaO2, MgO2 are peroxides, each O is 1-IMP -- EXCEPTION #2 – when oxygen is combined with FLOURINE, its oxidation state is 1+ or 2+. Fluorine is electronegative enough to oxidize oxygen.EXAMPLE :in FO the oxygen is +1, in F2O each oxygen is 2+ • Fluorine is always 1- in its compounds

  8. THE HYDROGEN RULE: THE OXIDATION STATE OF HYDROGEN IS USUALLY 1+EX in H2O each hydrogen is 1+IMP-EXCEPTION – in GROUP 1 METAL HYDRIDES the hydrogen is 1-, hydrogen is electronegative enough to oxidize group one metals. EX: NaH, KH etc the hydrogen is 1- USE CAUTION IN BINARY COMPOUNDS OF OXYGEN AND HYDROGEN -- CHECK FOR RULE EXCEPTIONS.

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