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Section 7.3

Section 7.3. Names and Formulas For Ionic Compounds. Naming Compounds. Name of a student _________ _________ first last Name of an ionic compound sodium chloride Which substance lost electrons? Which substance gained electrons?.

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Section 7.3

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  1. Section 7.3 Names and Formulas For Ionic Compounds

  2. Naming Compounds Name of a student _________ _________ first last Name of an ionic compound sodium chloride Which substance lost electrons? Which substance gained electrons?

  3. Formula Unit Chemical compound of an ionic compound Simplest ration of the ions involved

  4. Magnesium Chloride Magnesium group 2 Mg2+ Chlorine group 17 Cl- Want net charge of zero: Have 2+ and 1- Want 2+ and 2- so need 2 Cl- Ratio 1:2 MgCl2

  5. Ratios Determine the ratio from the formula units Ag2S MgCl2 Al2O3

  6. On Your Own Determine the ratio SnF4 FeO

  7. Monatomic Ions One-atom ion Mg2+ Br- Use the periodic table. What is the formula for beryllium ion? Iodide ion? Nitride ion?

  8. Common Monatomic Ions

  9. Monatomic Metal Ions

  10. Continued

  11. Oxidation Numbers The charge on a monatomic ion Oxidation number or oxidation state Equals the number of electrons transferred from the atom to form the ion Notice some ions have more than one oxidation state – with the d orbital elements

  12. Binary Ionic Compounds Symbol Cation then Anion Subscripts equals number of ions if no subscript then it is 1

  13. How to figure the Formula Write the symbol and charge for each ion Find the ratio of ions in the formula • Overall charge must be zero • Subscripts times the charges sum to zero

  14. Example 7.1 Determine the formula for the ionic compound formed from potassium and oxygen. Potassium group 1 K+ Oxygen group 16 O2- Ratio: 2:1 K2O Evaluate: 2 K ions (+1) + 1 O ion (-2) = 2 (+1) + 1(-2) = 2 + (-2) = 0

  15. Example 7.2 Determine the formula for the compound formed from aluminum ions and sulfide ions. Aluminum group 13 Al3+ Sulfur group 16 S2- Ratio: 2:3 Al2S3 Evaluate: 2 Al ions (3) + 3 S ions (-2) = 2 (3) + 3 (-2) = 6 + (-6) = 0

  16. Practice Write the ionic compound formula. • Potassium and iodide • Magnesium and chloride • Aluminum and bromide • Cesium and nitride • KI • MgCl2 • AlBr2 • Cs3N

  17. Polyatomic Ionic Compounds Ionic compounds made from more than one atom. Popular ions Ammonium NH4+ Nitrite NO2- Nitrate NO3- Hydroxide OH- Cyanide CN-

  18. Formulas for Polyatomic Ionic Compounds Mg(NO3)2 Mg2+ + (NO3)- ratio 1:2 Al(NO3)3 Al3+ + (NO3)- ratio 1:3 Use parenthesis to surround the polyatomic ion

  19. Write the formula for ionic compounds. Sodium and nitrate Calcium and chlorate Aluminum and carbonate 24. Ratio 1:1 Na+ + (NO3)-Na(NO3) 25. Ratio 1:2 Ca2+ + (ClO3)- Ca(ClO3)2 26. Ratio 2:3 Al3++(CO3)2- Al2(CO3)3 Practice

  20. Naming Ionic Compounds • Name the cation followed by the anion • For monatomic cations use the element name • For monatomic anions change the suffix to –ide. CsBr Cesium Bromide Rule 1 Rule 2 Rule 3

  21. 4. To distinguish between multiple oxidation numbers of the same element use (roman numerals) after the symbol. Fe2+ + O2-  FeO Iron (II) Oxide Fe3+ + O2-  Fe2O3 Iron (III) Oxide

  22. When the compound contains a polyatomic ions use the polyatomic ion name. NaOH is sodium hydroxide (OH)- (NH4)2S is ammonium sulfide (NH4)+

  23. Naming Ionic Compounds Yes No

  24. Practice Problems Name the following compounds. • NaBr • CaCl2 • KOH • Cu(NO3)2 • Ag2CrO4

  25. Each Student Make a 5 x 5 chart Across the top write 5 non-metal ions, with one polyatomic anion Along the side list 5 metals, with ammonium ion. Trade charts with another student, name each compound in the boxes. Trade back and check.

  26. Summary A formula unit gives the ratio of cations to anions in the ionic compound. A monatomic ion is formed from one atom. The charge of amonatomic ion is its oxidation number. Roman numerals indicate the oxidation number of cations having multiple possible oxidation states.

  27. Polyatomic ions consist of more then one atom and act as a single unit. To indicate more than one polyatomic ion in a chemical formula, place parentheses around the polyatomic ion and use a subscript.

  28. Practice Problems • State the order in which the ions associated with a compound composed of potassium and bromine would be written in the chemical formula and the compound name. • Describe the difference between a monatomic ion and a polyatomic ion, and give an example of each.

  29. 36. Ion X has a charge of 2+ and ion Y has a charge of 1-. Write the formula unit of the compound formed from the ions. • State the name and formula for the compound formed from Mg and Cl. • Write the name and formula for the compound formed from sodium ions and nitrite ions.

  30. Exit Ticket This is the formula for making artificial ocean water often used in saltwater aquariums. Mix 24.72g NaCl, 0.67g KCl, 1.36g CaCl, 4.66g MgCl2, 6.29g MgSO4 and 0.18g NaHCO3. Name each ionic compound.

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