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Chemistry Unit 6 Chemical Formulas and Chemical Compounds Heart cell rhythm depends on the opening and closing of a complex series of valves on the cell membrane, called ion channels. Some valves let certain ions like potassium (K+) flow out, others let different ions like sodium (Na+) flow in. There are also pumps that actively move ions one direction or another. Elements combine to form bonds Covalent Bonds -Electrons are shared -Usually between two nonmetals Ionic Bonds -Electrons are transferred -Usually between a metal and a non-metal or polyatomic ions EXAMPLE: carbon dioxide EXAMPLE: sodium chloride Different systems of naming depending on the type of bond…BE CAREFUL! Ions • Cation: A positive ion • Mg2+, NH4+ • Anion: A negative ion • Cl-, SO42• Ionic Bonding: Force of attraction between oppositely charged ions. Bohr Model of Sodium +1 How many many Now, What’s Howhow many the electrons electrons does net protons chargedoes on does Na Na Na? Nahave? have? have? Protons: 11 × +1 = 11 Electrons: 10 11 × -1 = -11 -10 +1 0 Na How Now Does How many does can Na valence Na satisfy we satisfy satisfy electrons thethe the octet octet octet does rule? Na rule? rule? have? Predicting Ionic Charges Group 1: Lose 1 electron to form 1+ ions H+ Li+ Na+ K+ Predicting Ionic Charges Loses 2 electrons to form Group 2: 2+ ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+ Predicting Ionic Charges B3+ Al3+ Ga3+ Group 13: Loses 3 electrons to form 3+ ions Predicting Ionic Charges Neither! Group 14 elements rarely form ions. Group 14: Lose 4 electrons or gain 4 electrons? Bohr Model of Phosphorous What is the net charge of P? -3 Protons: 15 × +1 = 15 Electrons: 18 × -1 = -18 -3 P How Now many does valence P we satisfy electrons octet does rule? P rule? have? Does How Pcan satisfy satisfy thethe octet the rule? octet Predicting Ionic Charges N3- Nitride P3- Phosphide As3- Arsenide Group 15: Gains 3 electrons to form 3- ions Predicting Ionic Charges O2- Oxide S2- Sulfide Se2- Selenide Group 16: Gains 2 electrons to form 2- ions Predicting Ionic Charges F1- Fluoride Br1- Bromide Cl1-Chloride I1- Iodide Group 17: Gains 1 electron to form 1- ions Predicting Ionic Charges Group 18: Stable Noble gases do not form ions! Predicting Ionic Charges Groups 3 - 12: Many transition elements have more than one possible oxidation state. Iron (II) = Fe2+ Iron (III) = Fe3+ Predicting Ionic Charges Groups 3 - 12: Some transition elements have only one possible oxidation state. Zinc = Zn2+ Silver = Ag+ Cadmium = Cd2+ Writing Ionic Compound Formulas Example: Barium nitrate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. (If so, skip to step 5) 3. Balance charges , if necessary, using subscripts. A. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion. B. Use parentheses if you need more than one ( Ba NO33)2) 2 Ba(NO of a polyatomic ion. 4. Check the subscripts and divide them by their largest common factor to give the smallest possible whole-number ratio. 5. Write the formula without the charges. 2+ Not balanced! Writing Ionic Compound Formulas Example: Ammonium sulfate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. (If so, skip to step 5) 3. Balance charges , if necessary, using +) 2- ( (NH NH4 4)SO 4 4 2SO subscripts. A. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion. B. Use parentheses if you need more than one of a polyatomic ion. 4. Check the subscripts and divide them by their largest common factor to give the smallest possible whole-number ratio. 5. Write the formula without the charges. 2 Not balanced! Writing Ionic Compound Formulas Names ending in –ide usually, but not always, represent an element 1. Write the formulas for the cation and anion,from the periodic table. including CHARGES! 2. Check to see if charges are balanced. (If so, skip to step 5) Example: Iron (III) chloride 3. Balance charges , if necessary, using subscripts. A. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion. B. Use parentheses if you need more than one of a polyatomic ion. 4. Check the subscripts and divide them by their largest common factor to give the smallest possible whole-number ratio. 5. Write the formula without the charges. 3+ Fe Cl FeCl - 3 3 Not balanced! Writing Ionic Compound Formulas Example: Aluminum sulfide 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. (If so, skip to step 5) 3. Balance charges , if necessary, using subscripts. A. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion. B. Use parentheses if you need more than one of a polyatomic ion. 4. Check the subscripts and divide them by their largest common factor to give the smallest possible whole-number ratio. 5. Write the formula without the charges. 3+ Al S Al S 2- 22 33 Not balanced! Writing Ionic Compound Formulas Example: Magnesium carbonate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. (If so, skip to step 5) 5. Write the formula without the charges. CO33 MgCO 2+ Mg 2- They are balanced! Practice Problem Questions 1-4 refer to the following generic chemical formulas. Which of the above represents the chemical formula when A and B are combined? A.AB B.AB2 C. A2B D.AB3 E.A2B3 1. A=Be 2. A=ammonium 3. A=Al 4. A=Ca B=Br B=O B=NO3-1 B=O Naming Ionic Compounds • 1. Cation first, then anion • 2. Monatomic cation = name of the element • Ca2+ = calcium ion • 3. Monatomic anion = root + -ide • Cl- = chloride • CaCl2 = calcium chloride 4. For polyatomic ions, use the name of that polyatomic ion. You Practice!! Name the following compounds: • • • • • • • MgCl2 Ag2O Ca(OH)2 SrS KClO3 NH4OH KClO • • • • • • • Magnesium Chloride Silver Oxide Calcium Hydroxide Strontium Sulfide Potassium Chlorate Ammonium Hydroxide Potassium Hypochlorite Naming Ionic Compounds (continued) Metals with multiple oxidation states - some metal forms more than one cation - use Roman numeral in name • PbCl2 • Pb2+ is cation • PbCl2 = lead (II) chloride How do we know that lead was +2? The oxidation number of lead is +2. +2 -2 PbCl -1 2 What is the charge of chlorine ion? How many chlorine ions does PbCl2 have? What’s the total charge of the chlorine ions? Compounds are neutral, so what must the charge of lead be in order to balance the -2 charge of chlorine? Let’s try Fe2O3 The oxidation number of iron is +3. +6 -6 Fe 2 O3 +3 Iron III Oxide -2 What is the charge of oxygen ion? How many oxygen ions does Fe2O3 have? What’s the total charge of the oxygen ions? What must the charge of iron be in order to balance the -6 charge of the oxygens? You practice!!! Name the following compounds: • CuO • CoF3 • SnI4 • FeSO4 • Sn(SO4)2 Copper II Oxide Cobalt III Fluoride Tin IV Iodide Iron II Sulfate Tin IV Sulfate Naming Binary Covalent Compounds • • • • • Compounds between two nonmetals - First element in the formula is named first. - Second element is named as if it were an anion. - Use prefixes - Only use mono on second element - 1 2 3 4 5 – mono – di – tri – tetra - penta 6 – hexa 7 – hepta 8 – octa 9 – nona 10 – deca P2O5 = diphosphorus pentoxide CO2 = carbon dioxide CO = carbon monoxide N2O = dinitrogen monoxide Pause for a Cause #4 Write the formula of the following compounds (WRITE WHAT YOU SEE DO NOT CHECK OXIDATION STATE!) a.Phosphorus Pentachloride b.Carbon Tetrafluoride c.Dinitrogen Pentaoxide d.Tetraphosphorous Decaoxide e.Carbon Monoxide f. Carbon Disulfide Diatomic Elements H2 N2 O2 F2 Cl2 Br2 I2 These elements exist in nature as diatomic molecules. They are most commonly joined to another element and not found alone in nature. Why? Acid Nomenclature • Acids • Compounds that form H+ in water. • Formulas usually begin with ‘H’. • Examples: • HCl (aq) – hydrochloric acid • HNO3 – nitric acid • H2SO4 – sulfuric acid Acid Nomenclature Anion Ending Binary Acid Name -ide hydro-(stem)-ic acid -ate (stem)-ic acid -ite (stem)-ous acid Ternary An easy way to remember which goes with which… “In the cafeteria, you ATE something ICky” Acid Nomenclature Flowchart ACIDS start with 'H' 2 elements 3 elements hydro- prefix -ic ending no hydro- prefix -ate ending becomes -ic ending -ite ending becomes -ous ending Acid Nomenclature • HBr (aq) • 2 elements, -ide hydrobromic acid carbonic acid sulfurous acid • H2CO3 • 3 elements, -ate • H2SO3 • 3 elements, -ite Acid Nomenclature • hydrofluoric acid • 2 elements H+ F- HF (aq) • sulfuric acid • 3 elements, -ic H+ SO42- H2SO4 • nitrous acid • 3 elements, -ous H+ NO2- HNO2 Name ‘Em! • HI (aq) • HCl • H2SO3 • HNO3 • HIO4 Write the Formula! • Hydrobromic acid • Nitrous acid • Carbonic acid • Phosphoric acid • Hydrotelluric acid Hydrocarbons - molecules that possess hydrogen and carbon Alkanes – hydrocarbons with only C-C single bonds. Example: Butane CH3CH2CH2CH3 C4H10 CnH2n+2 Alkenes – hydrocarbons with C=C double bonds. Example: Butene CH3CH=CHCH3 Alkynes – hydrocarbons with C Example: Butyne CH3C C4H8 CnH2n C triple bonds. CCH3 C4H6 CnH2n-2 Alcohols – R-OH (-OH is hydroxyl group, NOT hydroxide) Example: CH3OH Methanol Basic Naming of Hydrocarbons Hydrocarbon names are based on: 1) type, 2) # of carbons, 3) side chain type and position 1) name will end in -ane, -ene, or -yne 2) the number of carbons is given by a “prefix” 1 meth- 2 eth- 3 prop- 4 but- 5 pent6 hex- 7 hept- 8 oct- 9 non- 10 decActually, all end in a, but a is dropped when next to a vowel. E.g. a 6 C alkene is hexene Q - What names would be given to these: 7C, 9C alkane heptane, nonane 2C, 4C alkyne ethyne, butyne 1C, 3C alkene methene, propene Mnemonic for First Four Prefixes First four prefixes • • • • MethEthPropBut- Monkeys Eat Peeled Bananas Other Prefixes Decade ? Decimal • Pent• Oct- • Dec- Decathalon • Hex-, Hept-, Non- Organic Compounds Containing Oxygen • An alcohol is a compound obtained by substituting a hydroxyl group (-OH) for an –H atom on a carbon atom of a hydrocarbon group. • Some examples are CH3 OH CH3 CH2 OH methanol ethanol OH CH3 CH propanol CH3 Practice-Give the name or formula a. b. c. d. Butane Pentene Methanol C2H4 e. C7H15OH If given the formula…….. • 1st determine if the compound is a binary (molecular) compound – If all the elements in the compound are non-metals or metalloids the compound is a binary compound. – Use prefixes to name the compound. – CHARGES DON’T MATTER, DON’T WRITE CHARGES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! – DON’T SWITCH THE PREFIXES!!!!!!!!!!!!!!!!!!!! If given the formula…….. • If the compound is not a binary compound, name the compound like an ionic compound. – Use roman numerals to depicted the charge for Pb, Sn, and transition metals (except Zn, Ag, Cd). If given the name….. • 1st check for prefixes. – If prefixes are present, the compound is probably a binary compound. – DON’T WORRY ABOUT CHARGES, DON’T WRITE CHARGES, JUST WRITE WHAT YOU SEE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! – ***Remember some polyatomic ions have prefixes (bicarbonate, dichromate, dimercury). Write these like ionic compounds. If given the name….. • If the compound is not a binary compound, use the rules for writing ionic compounds. – Make sure to use the correct charges. – Make sure you don’t change the subscripts of the polyatomic ions. – THE ANSWER DOES NOT HAVE ANY CHARGES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Rules for oxidation numbers 1. Oxidation number for elements is zero. N2, O2, Na(s),Co(s), He (g) 2. Oxidation number of monatomic ions is the same as their charge Group IA = +1 Al3+, Zn2+, Cd2+, Ag+ Group IIA = +2 3. Oxidation number of oxygen in most compound is –2. Exceptions: O2- (peroxides)–1 4. Oxidation number of hydrogen is +1 with Non-metals and -1 with metals. Rules for Oxidation Numbers 1. All elements are zero: Oxidation # Rules for Oxidation Numbers 1. All elements are zero: N2 Oxidation # Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 0 Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 Pb 0 Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 0 Pb 0 Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 0 Pb 0 Na Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 0 Pb 0 Na 0 Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 0 Pb 0 Na 0 O2 Rules for Oxidation Numbers 1. Oxidation # All elements are zero: N2 0 Pb 0 Na 0 O2 0 Rules for Oxidation Numbers 2. Ions are their charge Na+ Oxidation # Rules for Oxidation Numbers 2. Oxidation # Ions are their charge Na+ +1 Rules for Oxidation Numbers 2. Oxidation # Ions are their charge Na+ Br- +1 Rules for Oxidation Numbers 2. Oxidation # Ions are their charge Na+ +1 Br- -1 Rules for Oxidation Numbers 3. The oxidation number of O in a compound is –2. Na2O Oxidation # Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2. Na2O -2 Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2. Na2O CO2 -2 Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2. Na2O -2 CO2 -2 Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2. Na2O -2 CO2 -2 O2 Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2. Na2O -2 CO2 -2 O2 0 Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2 or in peroxides -1. Na2O -2 CO2 -2 O2 0 HOOH Rules for Oxidation Numbers 3. Oxidation # The oxidation number of O in a compound is –2 or in peroxides -1. Na2O -2 CO2 -2 O2 0 HOOH -1 Rules for Oxidation Numbers 4. The oxidation number for H in a compound is +1. Oxidation # Rules for Oxidation Numbers 4. The oxidation number for H in a compound is +1. H2O Oxidation # Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1. H2O +1 Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1 H2O C12H24O11 +1 Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1 H2O +1 C12H24O11 +1 Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1 H2O +1 C12H24O11 +1 H2 Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1 H2O +1 C12H22O11 +1 H2 0 Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1 or in metal hydrides -1. H2O +1 C12H24O11 +1 H2 NaH 0 Rules for Oxidation Numbers 4. Oxidation # The oxidation number for H in a compound is +1 or in metal hydrides -1. H2O +1 C12H24O11 +1 H2 NaH 0 -1 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # 2SO4 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s 2SO4 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2SO4 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2SO4 Total charge Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2SO4 Total charge -8 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2SO4 Total charge -8 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2SO4 Total charge +6 -8 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s +6 -2 2SO4 Total charge +6 -8 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s +6 -2 2SO4 Total charge +6 -8 = -2 +6 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # 3PO4 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s 3PO4 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 3PO4 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 3PO4 Total charge Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 3PO4 Total charge -8 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 3PO4 Total charge -8 = -3 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 3PO4 Total charge +5 -8 = -3 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s +5 -2 3PO4 Total charge +5 -8 = -3 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s +5 -2 3PO4 Total charge +5 -8 = -3 +5 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # 2Cr2O7 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s 2Cr2O7 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2Cr2O7 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2Cr2O7 Total charge Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2Cr2O7 Total charge -14 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2Cr2O7 Total charge -14 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 2Cr2O7 Total charge +12 -14 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s -2 Divide by 2 2Cr2O7 Total charge +12 -14 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s +6 -2 2Cr2O7 Total charge +12 -14 = -2 Rules for Oxidation Numbers 5. the the All other oxidation numbers are assigned so that sum of all of the oxidation numbers is equal to charge on the chemical species. Oxidation # oxidation #s +6 -2 2Cr2O7 Total charge +12 -14 = -2 +6 Oxidation # Ca(NO3)2 Oxidation # +2 Ca(NO3)2 Oxidation # +2 Ca(NO3)2 +2 Oxidation # Na2C2O4 Oxidation # +1 -2 Na2C2O4 +2 -8 = 0 Oxidation # +1 -2 Na2C2O4 +2 +6 -8 = 0 Oxidation # +1 +3 -2 Na2C2O4 +2 +6 -8 = 0 +3 Oxidation # CH3COOH Oxidation # Rewrite C2H4O2 Oxidation # Rewrite +1 -2 C2H4O2 +4 -4 = 0 0 Oxidation # Zn(OH)42- Oxidation # +2 -2 +1 Zn(OH)42- +2 -8 +4 = -2 +2 Oxidation # H2PtCl6 Oxidation # +1 +4 -1 H2PtCl6 +2 +4 -6 = 0 +4 Oxidation # Al(NO3)3 Oxidation # +3 +5 -2 Al(NO3)3 +3 +15 -18 = 0 +5 Oxidation # H3PO3 Oxidation # +1 +3 -2 H3PO3 +3 +3 -6 = 0 +3 Oxidation # Na2O2 Oxidation # +1 -2 Na2O2 +2 -4 = 0 Exception - does not work, O must be 1 Oxidation # +1 -1 -1 Na2O2 +2 -2 = 0 Exception - does not work, O must be 1 Oxidation # CaH2 Oxidation # +2 +1 CaH2 +2 +2 = 0 Exception - does not work, H must be -1 Oxidation # +2 -1 -1 CaH2 +2 -2 = 0 Exception - does not work, H must be -1 Oxidation # Fe(H2O)5(OH)2+ Oxidation # 0 -1 Fe(H2O)5(OH)2+ Water has a charge of 0 OH has a charge of -1 Oxidation # 0 -1 Fe(H2O)5(OH)2+ ? + 0 -1 = +2 Oxidation # 0 -1 Fe(H2O)5(OH)2+ ? + 0 -1 +3 = +2 Assign oxidation numbers to all of the elements: Li2O Li = +1 O = -2 PF3 P = +3 F = -1 HNO3 H = +1 MnO4- N = +5 O = -2 Mn = +7 O = -2 Cr2O72- Cr = +6 O = -2 What is the oxidation state of the highlighted eleme P2O5 +5 diphosphorous pentoxide NaH -1 sodium hydride SnBr4 +4 tin (IV) bromide BaO2 -1 barium peroxide