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Starter 1/8

Starter 1/8. Pull out Homework (SG 7.1-2) Write the formula for sodium sulfate and determine the number of atoms in one unit. Ch. 7: Chemical Formulas and Names. Oxidation States. Oxidation States. Also called oxidation numbers For an individual atom of one type

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Starter 1/8

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  1. Starter 1/8 • Pull out Homework (SG 7.1-2) • Write the formula for sodium sulfate and determine the number of atoms in one unit.

  2. Ch. 7: Chemical Formulas and Names Oxidation States

  3. Oxidation States • Also called oxidation numbers • For an individual atom of one type • Used to indicate approximate electron distribution in covalent bonding • What contains covalent bonding? • molecular compounds • polyatomic ions • Not “real” charges since electrons are shared

  4. Oxidation States • Shared electron are counted as “belonging” to the more electronegative element • Since it has a greater attraction for the electrons • The electrons are actually located closer to that atom • Periodic Trend for electronegativity: increases as you go up and go to the right

  5. Assigning Oxidation States • Atoms in a pure element have an oxidation state of zero. • Na, O2, Fe, etc. • The more electronegative element is assigned a negative oxidation state while the less electronegative has a positive state • CF4: • C is less electronegative: + • F is more electronegative: -

  6. Assigning Oxidation States • Fluorine always has a -1 oxidation state • Since it is the most electronegative element • Oxygen usually has a -2 • Except in peroxides where it has a -1 • Hydrogen usually has a +1 • But when it is paired with a metal, it has a -1: ex. LiH

  7. Assigning Oxidation States • Sum of the oxidation states must equal zero in a neutral compound • N2O5 • O: -2 x 5 = -10 • N: +5 x 2 = +10 • Sum of states in a monatomic/polyatomic ion must equal the charge of the ion • NO3-1 • O: -2 x 3 = -6 • N: + 5 x 1 = +5

  8. UF6 F: -1 0 overall U: +6 to balance 6x-1 H2SO4 H: +1 O: -2 0 overall S: +6 to balance (4x-2)+(2x+1) ClO31- O: -2 -1 overall Cl: +5 to balance 3x-2 CO2 O: -2 0 overall C: +4 Practice

  9. Br2 Br: 0 NH3 H: +1 N: -3 CaSO3: Ca: +2 O: -2 S: +4 HSO3- H: +1 O: -2 -1 overall S: +4 B2H6 H: +1 0 overall B: +3 Determine the Oxidation States

  10. Using Oxidation States in Naming • Can use Stock System (Roman Numerals) to names molecular compounds too • The Roman Numeral in between names is the oxidation state of the first element • Do NOT simplify the ratio for molecular compounds • Only use either prefixes OR Roman Numerals, not a combination

  11. Stock System Naming • PCl3 • Cl: -1, P: +3 • Phosphorus (III) chloride • PCl5 • Cl: -1, P: +5 • Phosphorus (V) chloride • N2O • O: -2, N: +1 • Nitrogen (I) oxide

  12. Stock System Naming • CO • O: -2, C: +2 • Carbon (II) oxide • BrF5 • F: -1, Br: +5 • Bromine (V) fluoride • CO2 • O: -2, C: +4 • Carbon (IV) oxide

  13. Nitrogen (II) oxide N: 2+ O: -2 NO Lead (IV) oxide Pb: +4 O: -2 Pb2O4 PbO2 Sulfur (IV) fluoride S: +4 F: -1 SF4 Chlorine (III) fluoride Cl: +3 F: -1 ClF3 Writing Formulas

  14. Phosphorus (V) oxide P: +5 O: -2 P2O5 Boron (III) hydride B: +3 H: -1 BH3 Hydrogen (I) oxide H: +1 O: -2 H2O carbon (IV) sulfide C: +4 S: -2 CS2 Writing Formulas

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