Dry Lab 2A Objective

1
Dry Lab 2A Objective

• Become familiar with the oxidation numbers of
  various elements.

2
Dry Lab 2A - Introduction

• Benefits of standardized nomenclature
• International communication
• gt18 million compounds registered in the ACS CAS
  database.
• Patents
• Ions elements or groups of chemically bonded
  elements that have charge
• Cations positive charge Na, Fe2, Fe3
• Anions negative charge Cl-, CO32-, PO43-

3
Dry Lab 2AIntroduction contd

• Binary compounds compounds consisting of only
  two elements (CO2)

4
Dry Lab 2AIntroduction contd Nomenclature Rules

• Any element in the free state (not combined with
  any other element) has an oxidation number of 0
  (Ne, O2, S8)
• Monoatomic ions have a charge equal to the charge
  of the ion (Ca2 2, Fe3 3, Cl- 1-)
• Oxygen in compounds is usually assigned an
  oxidation number of -2.

5
Dry Lab 2AIntroduction contd Nomenclature
Rules contd

• Hydrogen in compounds usually has an oxidation
  number of 1
• 1
• A. Group 1A elements always have a charge of
  1 in compounds
• B. Group 2A elements always have a charge of
  2 in compounds
• C. B and Al always have oxidation numbers of
  3 in compounds

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Dry Lab 2AIntroduction contd Nomenclature
Rules contd

• 1
• D. In binary compounds with metals, Group 6A
  nonmetals have a charge of 2-.
• E. In binary compounds with metals, Group 7A
  elements have a charge of 1-.

7
Dry Lab 2AIntroduction contd Nomenclature
Rules contd

• Polyatomic ions have a charge equal to the sum of
  the oxidation numbers of the group.
• Ex SO42- S6, 4 O 4x2--8,
• 6 -8 -2
• Ex PO43- P5, 4 O 4x2--8,
• 5 -8 -3

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Dry Lab 2AIntroduction contd Nomenclature
Rules contd

• The element closest to fluorine (the most
  electronegative element) is always assigned the
  negative number.
• For compounds, the sum of the charges and
  oxidation numbers must equal zero. For
  polyatomic ions, the sum of the oxidation numbers
  must equal the charge of the ion.

9
Dry Lab 2AIntroduction contd Nomenclature
Rules contd

• Some elements may have more than one charge
  depending on the compound they are in.
• Ex FeCl2 and FeCl3. Chlorine always has a
  charge of 1- (rule 5E), irons charge will change
  from 2 in FeCl2 to 3 in FeCl3.

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2A - Procedure/Questions

• Part 1 a, c
• Part 2 a, c
• Part 3 a, c
• Part 4 a, c
• Hand in on notebook paper.

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Dry Lab 2B Objective

• To name and write formulas for the binary
  compounds of
• Metal and a nonmetal
• Two nonmetals (or non-metal and metalloid)
• Acids
• Metalloid an element having the appearance of a
  metal but displaying nonmetallic properties.

12
Dry Lab 2B Introduction

• The oxidation number of an element helps us to
  write the formula of a compound and to
  characterize the chemical nature of the element
  in the compound.
• Binary compounds Simplest compounds, consisting
  of only two elements, not necessarily two atoms
  (NaCl, Cr2O3)

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Dry Lab 2B Rules/Examples

• Two Elements named directly from the elements
  themselves. In a binary salt, the metal is named
  first and the second element has ide added to it.
  
• Ex CaC2 Calcium carbide
• NH4CN Ammonium cyanide
• Both ammonium (NH4) and cyanide (CN-) ions are
  exceptions to the above rule (non-binary).

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Dry Lab 2B Rules/Examples

• ic ous and Stock systems
• Old (ic ous) system ic or ous is added as a
  suffix to the root of the Latin name for the
  metal.
• ous lower charge Fe2ferrous
• ic higher charge Fe3ferric

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Dry Lab 2B Rules/Examples

• ic ous and Stock systems contd
• Stock system a Roman numeral is placed after
  the English name indicating the charge Iron
  (II), Iron (III)
• CuCl Cuprous Chloride or Copper (I) Chloride
• Hg2Cl2 Mercury (I) Chloride or Mercurous
  Chloride
• HgCl2 Mercury (II) Chloride or Mercuric Chloride

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Dry Lab 2B Rules/Examples

• Two non-metals or a metalloid and a nonmetal
• Greek prefixes mono-, di-, tri-, etc (see table
  on p. 129)
• SO3 sulfur trioxide
• N2S4 dinitrogen tetrasulfide

17
Dry Lab 2B Rules/Examples

• Hydrates inorganic salts with loosely bound
  water molecules.
• Name salt as before and add hydrate (H2O) with
  Greek prefix
• CoBr3?6H2O Cobalt (III) bromide hexahydrate
• Binary acids an aqueous solution formed by
  hydrogen and a non-metal.
• The prefix hydro and suffix ic are added to the
  name of the nonmetal
• HI Hydroiodic acid
• HCl Hydrochloric acid

18
2B - Procedure/Questions

• Part 1 a, c
• Part 2 a, c
• Part 3 a, c
• Part 4 a, c
• Part 5 a, c
• Part 6 a, c
• Part 7 a, c
• Hand in on notebook paper.

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Dry Lab 2C Objectives

• To name and write formulas for salts and acids
  containing polyatomic anions.
• To name and write formulas for acid salts.
• Acid salts are salts in which a metal cation
  replaces less than all of the hydrogens of an
  acid having more than one hydrogen (a polyprotic
  acid).

20
Dry Lab 2C Introduction

• Many polyatomic anions consist of one element
  (usu. a nonmetal) and oxygen the entire group
  carries a negative charge. To name the anion use
  the root name of the nonoxygen
• SO42- - sulfate ion
• NO3- - nitrate ion

21
Dry Lab 2C Introduction

• If an element and oxygen form two polyatomic
  anions, the anion with the element having the
  higher oxidation number uses the -ate suffix
  while the anion with the element having the lower
  oxidation number uses the -ite suffix.
• SO42- - S 6 sulfate
• SO32- - S 4 sulfite

22
Dry Lab 2C Introduction

• If more than 2 polyatomic anions are formed from
  an element and oxygen, the prefixes per- and
  hypo- are added.
• This happens most often among the polyatomic
  anions with a halogen as the element
• perchlorate - charge on Cl 7
• chlorate - charge on Cl 5
• chlorite - charge on Cl 3
• hypochlorite - charge on Cl 1

23
Dry Lab 2C Introduction

• Ternary Acids (Oxoacids) - compounds of hydrogen
  and a polyatomic anion. Naming these acids does
  not include the hydrogen. If the anion is named
  -ate, the acid is named using -ic. If the anion
  is -ite, the acid is named using -ous.
• SO42- - sulfate ion H2SO4 - sulfuric acid
• SO2- - sulfite ion H2SO3 - sulfurous
  acid

24
Dry Lab 2C Introduction

• Acid salts are salts in which a metal cation
  replaces less than all of the hydrogens of an
  acid having more than one hydrogen (polyprotic
  acid).
• NaHSO4 - sodium hydrogen sulfate
• CaHPO4 - calcium hydrogen phosphate
• NaHS sodium hydrogen sulfide

25
2C - Procedure/Questions

• Part 1 a, c
• Part 2 a, c
• Part 3 a, c
• Part 4 a, c
• Part 5 a, c
• Part 6 a, c
• Part 7 a, c
• Hand in on notebook paper.