Chapter 7 Chemical Formulas and  Chemical Compounds
Chemical Names & Formulas <ul><li>There are literally  thousands  of chemicals </li></ul><ul><li>Isn’t always best to use ...
<ul><li>Significance of chemical formulas: </li></ul><ul><ul><li>Gives relative number of atoms of each kind of element. <...
<ul><li>When parentheses are used you must multiply inside and out. </li></ul><ul><ul><li>Al 2 (SO 4 ) 3 </li></ul></ul><u...
Names of Binary Compounds <ul><li>Binary compounds  are those formed from only 2 elements. </li></ul><ul><li>To write thei...
Formulas of Binary Compounds <ul><li>To write the formula of a compound you must consider the charges and multiply by addi...
<ul><li>Ex: zinc is (2+) and iodine is (1-) so: </li></ul><ul><ul><li>Zn  2+  I  1- </li></ul></ul><ul><ul><li>ZnI 2 </li>...
<ul><li>How do you know the charge? </li></ul><ul><ul><li>Use the valence electrons </li></ul></ul><ul><ul><li>Group 1 = 1...
Stock System of Nomenclature <ul><li>Some transition metals have more than one possible charge: </li></ul><ul><li>Ex. Copp...
<ul><li>The charges of these elements  must  be represented in the name of the compounds. </li></ul><ul><li>Charges are pr...
<ul><li>How do you know how to write the formula??? </li></ul><ul><li>Iron (II) combines with oxygen </li></ul><ul><li>Fe ...
<ul><li>How do you know how to write the name if you only see the  formula ??? </li></ul><ul><li>CuBr 2 </li></ul><ul><li>...
<ul><li>Cu  Br 2 </li></ul>If charges are +1  -1 Then  +1  -2  ≠  0
<ul><li>Cu  Br 2 </li></ul>If charges are +2  -1 Then  +2  -2  =   0
Practice <ul><li>pg. 223 </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul><ul><li>pg. 225 </li></ul><ul><ul><li>C...
Compounds with Polyatomic Ions <ul><li>Many compounds are composed of polyatomic ions  (a group of covalently bonded atoms...
<ul><li>Most polyatomic ions end with “–ate” or “-ite” but there are a few exceptions: </li></ul><ul><ul><li>Cyanide (CN) ...
Naming Compounds with Polyatomic Ions <ul><li>Simply write the complete name of the positive element and the name of the p...
<ul><li>Writing the formulas for these compounds are a little trickier. </li></ul><ul><li>Make sure that you treat the pol...
<ul><li>Examples: </li></ul><ul><li>Potassium nitrate </li></ul>Symbols:  K   (NO 3 ) Charges:  +   - Totals:  1+  and  1-...
<ul><li>Examples: </li></ul><ul><li>Aluminum Sulfate </li></ul>Symbols:  Al   (SO 4 ) Charges:  3 +   2 - Add Subscripts :...
<ul><li>Polyatomic ions may be paired with  transition metals  that have multiple charges. </li></ul><ul><li>Ex:  Copper (...
Practice <ul><li>pg. 227  </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul>
Naming Binary  Molecular  Compounds <ul><li>Molecular compounds are those in which the elements are close together on the ...
<ul><li>Ex:  Compounds of Nitrogen and Oxygen </li></ul><ul><ul><li>N 2 O </li></ul></ul><ul><ul><li>NO </li></ul></ul><ul...
<ul><li>Prefixes indicate the number of atoms in the compound </li></ul><ul><li>1 atom:  Mono </li></ul><ul><li>2 atoms:  ...
<ul><li>The less electronegative element is written first and is given a prefix  only if it has more than one atom in the ...
Practice <ul><li>pg. 229  </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul>
Naming Acids and Salts <ul><li>Memorize  the formulas for the common acids. </li></ul><ul><li>All begin with one or more H...
<ul><li>Binary  acids contain only 2 elements </li></ul><ul><ul><li>Example:  Hydrochloric acid  HCl </li></ul></ul><ul><l...
<ul><li>When acids have less oxygen atoms than normal the names change: </li></ul><ul><ul><li>Normal HClO 3  is chloric ac...
Naming Salts <ul><li>Any ionic compound composed of a cation and the anion from an acid is referred to as a salt. </li></u...
Practice <ul><li>pg. 251 </li></ul><ul><ul><li>Complete # 15 </li></ul></ul>
<ul><li>Oxidation Numbers </li></ul>
Oxidation Numbers <ul><li>Oxidation numbers are numbers assigned to the atoms in a molecular compound or ion that indicate...
<ul><li>Rules for assigning oxidation numbers:  </li></ul><ul><ul><li>Atoms in a pure element have an oxidation number of ...
<ul><li>(Rules continued): </li></ul><ul><ul><li>Hydrogen’s ox. # is +1 unless it is with metals – then it is -1 </li></ul...
<ul><li>What are the oxidation numbers for each atom in these compounds? </li></ul><ul><li>UF 6  :  Fluorine is -1 x 6 = -...
<ul><li>What are the oxidation numbers for the chlorate polyatomic ion? </li></ul><ul><li>ClO 3 -   :  Oxygen is -2 x 3 = ...
<ul><li>pg. 252 </li></ul><ul><ul><li>Complete # 24 </li></ul></ul>Practice
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Chapter 7 Notes

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Chemistry Chapter 7 Notes

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Chapter 7 Notes

  1. 1. Chapter 7 Chemical Formulas and Chemical Compounds
  2. 2. Chemical Names & Formulas <ul><li>There are literally thousands of chemicals </li></ul><ul><li>Isn’t always best to use common names for chemicals (calcium carbonate is limestone, sodium chloride is salt, and hydrogen oxide is water) </li></ul><ul><li>Common names don’t give information about chemical composition. </li></ul>
  3. 3. <ul><li>Significance of chemical formulas: </li></ul><ul><ul><li>Gives relative number of atoms of each kind of element. </li></ul></ul><ul><ul><li>Subscripts : small numbers to the right that tell the number of atoms </li></ul></ul><ul><ul><li>If no subscript then it is understood to be 1 </li></ul></ul><ul><ul><li>H 2 SO 4 </li></ul></ul><ul><ul><li>2 hydrogens, 1 sulfur, 4 oxygen </li></ul></ul>
  4. 4. <ul><li>When parentheses are used you must multiply inside and out. </li></ul><ul><ul><li>Al 2 (SO 4 ) 3 </li></ul></ul><ul><ul><li>(2 Aluminums, 3 Sulfurs, 12 Oxygens) </li></ul></ul>
  5. 5. Names of Binary Compounds <ul><li>Binary compounds are those formed from only 2 elements. </li></ul><ul><li>To write their formulas the positive ion is written first and then the negative . </li></ul><ul><li>To name them use the complete name of the positive ion and add the negative ion name but change the ending to “-ide.” (Sulfur becomes sulfide, oxygen becomes oxide, phosphorous becomes phosphide) </li></ul>
  6. 6. Formulas of Binary Compounds <ul><li>To write the formula of a compound you must consider the charges and multiply by adding subscripts so that the overall charge on the compound is zero. </li></ul><ul><li>Ex: zinc is (2+) and sulfur is (2-) so: </li></ul><ul><ul><li>ZnS </li></ul></ul><ul><ul><li>Name: Zinc Sulfide </li></ul></ul>
  7. 7. <ul><li>Ex: zinc is (2+) and iodine is (1-) so: </li></ul><ul><ul><li>Zn 2+ I 1- </li></ul></ul><ul><ul><li>ZnI 2 </li></ul></ul><ul><ul><li>Name: Zinc Iodide </li></ul></ul>Subscripts 1 2 2 + 2- ( = 0 )
  8. 8. <ul><li>How do you know the charge? </li></ul><ul><ul><li>Use the valence electrons </li></ul></ul><ul><ul><li>Group 1 = 1+, Group 2 = 2+, 3+, 4 ± </li></ul></ul><ul><ul><li>Group 15 = 3-, Grp. 16 = 2-, Grp. 17 = 1- </li></ul></ul><ul><ul><li>Use charge chart (page 221) for transition metals. </li></ul></ul>
  9. 9. Stock System of Nomenclature <ul><li>Some transition metals have more than one possible charge: </li></ul><ul><li>Ex. Copper: Cu + and Cu 2+ </li></ul><ul><li> Iron: Fe 2+ and Fe 3+ </li></ul><ul><li> Lead: Pb +3 and Pb +4 </li></ul><ul><li> Tin: Sn +2 and Sn +4 </li></ul>
  10. 10. <ul><li>The charges of these elements must be represented in the name of the compounds. </li></ul><ul><li>Charges are provided by using Roman numerals in the names </li></ul><ul><li>Ex: Iron (II) oxide and Iron (III) oxide </li></ul><ul><li>Formulas: FeO Fe 2 O 3 </li></ul>
  11. 11. <ul><li>How do you know how to write the formula??? </li></ul><ul><li>Iron (II) combines with oxygen </li></ul><ul><li>Fe 2+ O 2- (charges equal zero so FeO) </li></ul><ul><li>Iron (III) combines with oxygen </li></ul><ul><li>Fe 3+ O 2- (add subscripts and multiply to equal zero </li></ul>2 3
  12. 12. <ul><li>How do you know how to write the name if you only see the formula ??? </li></ul><ul><li>CuBr 2 </li></ul><ul><li>The name is Copper Bromide but is it Copper (I) Bromide or Copper (II) Bromide??? </li></ul>
  13. 13. <ul><li>Cu Br 2 </li></ul>If charges are +1 -1 Then +1 -2 ≠ 0
  14. 14. <ul><li>Cu Br 2 </li></ul>If charges are +2 -1 Then +2 -2 = 0
  15. 15. Practice <ul><li>pg. 223 </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul><ul><li>pg. 225 </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul>
  16. 16. Compounds with Polyatomic Ions <ul><li>Many compounds are composed of polyatomic ions (a group of covalently bonded atoms that carry a charge) . </li></ul><ul><li>Examples of polyatomic ions: </li></ul><ul><ul><li>Sulfate (SO 4 ) 2- </li></ul></ul><ul><ul><li>Nitrate (NO 3 ) – </li></ul></ul><ul><ul><li>Phosphate (PO 4 ) 3- </li></ul></ul><ul><ul><li>Carbonate (CO 3 ) 2- </li></ul></ul><ul><ul><li>Dichromate (Cr 2 O 7 ) 2- </li></ul></ul><ul><ul><li>Ammonium (NH 4 ) + </li></ul></ul>
  17. 17. <ul><li>Most polyatomic ions end with “–ate” or “-ite” but there are a few exceptions: </li></ul><ul><ul><li>Cyanide (CN) - </li></ul></ul><ul><ul><li>Hydroxide (OH) - </li></ul></ul><ul><ul><li>Note of caution : </li></ul></ul><ul><ul><li>Don’t confuse these with binary compounds since they end in “ide.” </li></ul></ul>
  18. 18. Naming Compounds with Polyatomic Ions <ul><li>Simply write the complete name of the positive element and the name of the polyatomic ion. </li></ul><ul><li>KNO 3 = Potassium Nitrate </li></ul><ul><li>CaSO 4 = Calcium Sulfate </li></ul><ul><li>Al(OH) 3 = Aluminum Hydroxide </li></ul>
  19. 19. <ul><li>Writing the formulas for these compounds are a little trickier. </li></ul><ul><li>Make sure that you treat the polyatomic ion as a whole unit and do not change its subscripts! </li></ul><ul><li>(SO 4 ) 2- = 1 sulfate ion </li></ul><ul><li>(SO 4 ) 2- 2 = 2 sulfate ions NOT… </li></ul><ul><ul><ul><ul><ul><li>(S 2 O 8 ) </li></ul></ul></ul></ul></ul>
  20. 20. <ul><li>Examples: </li></ul><ul><li>Potassium nitrate </li></ul>Symbols: K (NO 3 ) Charges: + - Totals: 1+ and 1- = 0 Final Formula: KNO 3 (no parenthesis needed since only 1 ion is required
  21. 21. <ul><li>Examples: </li></ul><ul><li>Aluminum Sulfate </li></ul>Symbols: Al (SO 4 ) Charges: 3 + 2 - Add Subscripts : 2 3 Final Formula: Al 2 (SO 4 ) 3 (parenthesis must be used to show 3 sulfate ions) Totals : 6+ and 6- = 0
  22. 22. <ul><li>Polyatomic ions may be paired with transition metals that have multiple charges. </li></ul><ul><li>Ex: Copper (II) and sulfate = CuSO 4 </li></ul><ul><li>But Copper (I) and sulfate = Cu 2 SO 4 </li></ul><ul><li>When naming them the Roman numeral must be included. </li></ul><ul><li>Fe 3 (PO 4 ) 2 = Iron (II) Phosphate </li></ul>
  23. 23. Practice <ul><li>pg. 227 </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul>
  24. 24. Naming Binary Molecular Compounds <ul><li>Molecular compounds are those in which the elements are close together on the periodic table. </li></ul><ul><li>Ex: </li></ul><ul><ul><li>Nitrogen and Oxygen </li></ul></ul><ul><ul><li>Carbon and Oxygen </li></ul></ul><ul><ul><li>Sulfur and Oxygen </li></ul></ul><ul><ul><li>Phosphorus and Chlorine </li></ul></ul>
  25. 25. <ul><li>Ex: Compounds of Nitrogen and Oxygen </li></ul><ul><ul><li>N 2 O </li></ul></ul><ul><ul><li>NO </li></ul></ul><ul><ul><li>NO 2 </li></ul></ul><ul><ul><li>N 2 O 3 </li></ul></ul><ul><ul><li>N 2 O 5 </li></ul></ul><ul><li>Newer method of naming is to use the stock system with Roman Numerals. </li></ul><ul><li>Old traditional method uses prefixes . </li></ul>
  26. 26. <ul><li>Prefixes indicate the number of atoms in the compound </li></ul><ul><li>1 atom: Mono </li></ul><ul><li>2 atoms: Di </li></ul><ul><li>3 atoms: Tri </li></ul><ul><li>4 atoms: Tetra </li></ul><ul><li>5 atoms: Penta </li></ul><ul><li>6 atoms: Hexa </li></ul><ul><li>7 atoms: Hepta </li></ul><ul><li>8 atoms: Octa </li></ul><ul><li>9 atoms: Nona </li></ul><ul><li>10 atoms: Deca </li></ul>
  27. 27. <ul><li>The less electronegative element is written first and is given a prefix only if it has more than one atom in the formula. </li></ul><ul><li>Next element has a prefix indicating the number of atoms and ends typically with “ide.” </li></ul><ul><li>Examples: </li></ul><ul><ul><li>N 2 O </li></ul></ul><ul><ul><li>NO </li></ul></ul><ul><ul><li>NO 2 </li></ul></ul><ul><ul><li>N 2 O 3 </li></ul></ul><ul><ul><li>N 2 O 5 </li></ul></ul>Dinitrogen Monoxide Nitrogen Monoxide Nitrogen Dioxide Dinitrogen Trioxide Dinitrogen Pentoxide
  28. 28. Practice <ul><li>pg. 229 </li></ul><ul><ul><li>Complete #’s 1 and 2 </li></ul></ul>
  29. 29. Naming Acids and Salts <ul><li>Memorize the formulas for the common acids. </li></ul><ul><li>All begin with one or more H atoms. </li></ul><ul><ul><li>Sulfuric Acid H 2 SO 4 </li></ul></ul><ul><ul><li>Hydrochloric Acid HCl </li></ul></ul><ul><ul><li>Nitric Acid HNO 3 </li></ul></ul><ul><ul><li>Phosphoric Acid H 3 PO 4 </li></ul></ul><ul><ul><li>Carbonic Acid H 2 CO 3 </li></ul></ul>
  30. 30. <ul><li>Binary acids contain only 2 elements </li></ul><ul><ul><li>Example: Hydrochloric acid HCl </li></ul></ul><ul><li>Oxyacids contain hydrogen, oxygen, and one other element </li></ul><ul><ul><li>Example: Sulfuric acid H 2 SO 4 </li></ul></ul>
  31. 31. <ul><li>When acids have less oxygen atoms than normal the names change: </li></ul><ul><ul><li>Normal HClO 3 is chloric acid </li></ul></ul><ul><ul><li>Loss of 1 oxygen atom HClO 2 is chlor ous acid </li></ul></ul><ul><ul><li>Loss of 2 oxygen atoms HClO is hypochlorous acid </li></ul></ul><ul><ul><li>An extra oxygen atom HClO 4 is perchloric acid </li></ul></ul>
  32. 32. Naming Salts <ul><li>Any ionic compound composed of a cation and the anion from an acid is referred to as a salt. </li></ul><ul><li>Example: </li></ul><ul><ul><li>NaCl (anion from hydrochloric acid) </li></ul></ul><ul><ul><li>CaSO 4 (anion from sulfuric acid) </li></ul></ul>
  33. 33. Practice <ul><li>pg. 251 </li></ul><ul><ul><li>Complete # 15 </li></ul></ul>
  34. 34. <ul><li>Oxidation Numbers </li></ul>
  35. 35. Oxidation Numbers <ul><li>Oxidation numbers are numbers assigned to the atoms in a molecular compound or ion that indicates the general distribution of electrons among bonded atoms. </li></ul><ul><li>Oxidation numbers are not actual charges. </li></ul><ul><li>Oxidation numbers are useful in naming compounds and writing formulas. </li></ul>+2 -1 +3 +1 -2
  36. 36. <ul><li>Rules for assigning oxidation numbers: </li></ul><ul><ul><li>Atoms in a pure element have an oxidation number of zero – O 2 Ox. # = 0 </li></ul></ul><ul><ul><li>Fluorine always has ox. # of -1 </li></ul></ul><ul><ul><li>Oxygen almost always has ox. # of -2 except in peroxides such as H 2 O 2 – then it is a -1. </li></ul></ul>
  37. 37. <ul><li>(Rules continued): </li></ul><ul><ul><li>Hydrogen’s ox. # is +1 unless it is with metals – then it is -1 </li></ul></ul><ul><ul><li>The sum of the ox. # in molecules must be zero, but in polyatomic ions, it is equal to the ions charge. </li></ul></ul>
  38. 38. <ul><li>What are the oxidation numbers for each atom in these compounds? </li></ul><ul><li>UF 6 : Fluorine is -1 x 6 = -6 </li></ul><ul><li>Uranium +6 {+6 + (-6)} = 0 </li></ul><ul><li>H 2 SO 4 : Oxygen is -2 (x 4 = -8) </li></ul><ul><li>Hydrogen is +1 (x 2 = +2) so </li></ul><ul><li>Sulfur has to be +6 </li></ul><ul><li>{ (+6) + (+2) + (-8) }= 0 </li></ul>
  39. 39. <ul><li>What are the oxidation numbers for the chlorate polyatomic ion? </li></ul><ul><li>ClO 3 - : Oxygen is -2 x 3 = -6 </li></ul><ul><li>Chlorine must be +5 </li></ul><ul><li> { (+5) + (-6)} = -1 (the ion’s charge) </li></ul>
  40. 40. <ul><li>pg. 252 </li></ul><ul><ul><li>Complete # 24 </li></ul></ul>Practice

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