Ionic Compounds

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Ionic Compounds

  1. 1. COMPOUNDS part one: ionic compounds
  2. 2. <ul><li>A compound is a pure substance made up of </li></ul>COMPOUNDS are chemically combined two or more elements in which the elements + = Na Cl NaCl
  3. 3. <ul><li>There are two types of compounds: </li></ul>COMPOUNDS ionic molecular &
  4. 4. <ul><li>An ion is an atom or group of atoms that has either a positive charge or a negative charge </li></ul>IONIC COMPOUNDS
  5. 5. <ul><li>An ionic compound is formed from </li></ul>IONIC COMPOUNDS one or more positively charged ions and one or more negatively charged ions
  6. 6. <ul><li>Ions form when atoms of different </li></ul>IONIC COMPOUNDS elements combine by transferring electrons from one atom to another
  7. 7. <ul><li>For example, this process occurs when atoms of sodium metal ( Na ) combine with atoms of chlorine ( Cl ) to form sodium chloride ( NaCl ), or table salt </li></ul>IONIC COMPOUNDS + = Na Cl NaCl
  8. 8. <ul><li>During the formation of NaCl, one electron </li></ul>is transferred from a sodium atom to a chlorine atom IONIC COMPOUNDS
  9. 9. <ul><li>Each sodium atom loses one electron and </li></ul>IONIC COMPOUNDS becomes a positively charged ion Na + Na +
  10. 10. <ul><li>The symbol “ + ” is written as a superscript </li></ul>IONIC COMPOUNDS to indicate that the sodium has a charge of 1+ Na +
  11. 11. <ul><li>Each chlorine atom gains one electron </li></ul>Cl - IONIC COMPOUNDS to become a negatively charged ion Cl -
  12. 12. <ul><li>The symbol “ - ” is written as a superscript to </li></ul>indicate that the chlorine ion has a charge of 1- Cl - IONIC COMPOUNDS
  13. 13. <ul><li>Notice that both ions have 8 electrons in </li></ul>their outermost shell IONIC COMPOUNDS
  14. 14. <ul><li>Ions often form so that the outer shell is full , </li></ul>or contains the maximum number of electrons IONIC COMPOUNDS
  15. 15. <ul><li>Metal atoms tend to lose electrons </li></ul>Non-metal atoms tend to gain electrons IONIC COMPOUNDS
  16. 16. <ul><li>When an atom gives up one or more </li></ul>electrons it becomes positive called a cation (“cat-eye-on”)
  17. 17. <ul><li>When an atom gains one or more </li></ul>electrons it becomes negative called an anion (“an-eye-on”)
  18. 18. Ca + ions are posi + ive A n ions are n egative
  19. 19. <ul><li>The farther the valence electron is from its </li></ul>positive nucleus, the more easily it is removed and the more reactive the atom is
  20. 20. <ul><li>Reactivity generally increases for cations as you move down the periodic table ex.) potassium is more reactive than sodium </li></ul>CATIONS Lithium Sodium Potassium Rubidium Cesium
  21. 21. CATIONS reactivity increases
  22. 22. <ul><li>Reactivity generally decreases for anions as you move down the periodic table ex.) fluorine is more reactive than chlorine </li></ul>Fluorine Bromine Iodine Astatine ANIONS Chlorine
  23. 23. reactivity increases ANIONS
  24. 24. <ul><li>Ionic compounds have the following properties… </li></ul>IONIC COMPOUNDS
  25. 25. <ul><li>At room temperature, most are hard , </li></ul>IONIC COMPOUNDS brittle solids that can be crushed
  26. 26. <ul><li>Ionic compounds form crystals that have an alternating arrangement of positively charged ions and negatively charged ions, so that when they break their edges are well-defined </li></ul>IONIC COMPOUNDS
  27. 27. IONIC COMPOUNDS In an ionic crystal, every ion is attracted to every other ion in the crystal. As a result, ionic crystals have very high melting points ex.) NaCl melts at 800 o C
  28. 28. <ul><li>When an ionic compound dissolves in water, the crystal structure breaks down and the ions become free to move. </li></ul>IONIC COMPOUNDS
  29. 29. <ul><li>Solutions of ionic compounds can </li></ul>IONIC COMPOUNDS conduct electricity
  30. 30. <ul><li>A cation will react with an anion in order </li></ul>to acquire a full valence shell
  31. 31. <ul><li>When a cation reacts with an anion the new arrangement of valence electrons has less energy than the previous arrangement </li></ul>IONIC COMPOUNDS
  32. 32. <ul><li>noble gas that is closest on the periodic table </li></ul>For many atoms, this arrangement resembles the
  33. 33. <ul><li>A metal cation will have the same number of electrons as an atom of the closest noble gas with a lower atomic number </li></ul>CATIONS
  34. 34. <ul><li>For example, neon is the closest noble gas in the periodic table to sodium , magnesium and aluminum </li></ul>CATIONS
  35. 35. <ul><li>The cations Na + , Mg 2+ , and Al 3+ all have the same number of electrons as atoms of neon </li></ul>CATIONS Na 11p 12n +1 Al 13p 14n +3 Mg 12p 12n +2 Ne 10p 10n
  36. 36. <ul><li>Things to remember: </li></ul><ul><li>Not all atoms will form ions </li></ul><ul><li>Some atoms can form an ion in more than one way </li></ul><ul><li>Information on the periodic table will show you the ion charges for each element </li></ul>IONIC COMPOUNDS
  37. 37. <ul><li>To write the symbol for an ion, write the symbol of the element and show the ion charge as a superscript </li></ul><ul><li>ex.) the symbol of a calcium ion is Ca 2+ </li></ul><ul><li>When an ion has a charge of 1+ or 1- the symbol has no number in the superscript, such as Na + or F - </li></ul>ION SYMBOLS
  38. 38. <ul><li>When an element can form only one type of ion, the ion has the same name as the element </li></ul><ul><li>ex.) Ca 2+ = “ calcium ” </li></ul>ION NAMES Ca 20p 20n +2
  39. 39. <ul><li>A multivalent element is an element that can form an ion in more than one way </li></ul><ul><li>ex.) An atom of copper can form two different ions: Cu + or Cu 2+ </li></ul>ION NAMES
  40. 40. ION NAMES The name of an ion of a multivalent element always contains a Roman numeral that indicates the ion charge
  41. 41. <ul><li>For example, Cu + is named copper(I) (read as “copper one”) </li></ul><ul><li>Cu 2+ is named copper(II) (read as “copper two”) </li></ul><ul><li>Only multivalent metals have Roman numerals in their names </li></ul>ION NAMES
  42. 42. <ul><li>Name the metal ion first </li></ul><ul><ul><li>The name of the metal ion is the same as the element name </li></ul></ul><ul><ul><li>ex.) in KBr, the name of the K + ion is potassium </li></ul></ul><ul><ul><li>If the element can form an ion in more than one way, include a Roman numeral to indicate charge </li></ul></ul>NAMING IONIC COMPOUNDS K 19p 20n +1
  43. 43. <ul><li>Name the non-metal ion second </li></ul><ul><ul><li>When a non-metal becomes a negative ion, the ending of its name changes to “ide” </li></ul></ul><ul><ul><li>ex.) a brom ine atom (Br) gains an electron to become a brom ide ion (Br - ) </li></ul></ul>NAMING IONIC COMPOUNDS
  44. 44. NAMING IONIC COMPOUNDS iod ide  iod ine brom ide  brom ine chlor ide  chlor ine sulf ide  sulf ur phosph ide  phosph orous fluor ide  fluor ine ox ide  ox ygen nitr ide  nitr ogen
  45. 45. <ul><li>Name the ionic compound by combining the ion names </li></ul><ul><ul><li>The name of KBr is therefore “potassium bromide” </li></ul></ul>NAMING IONIC COMPOUNDS
  46. 46. <ul><li>The formulas of ionic compounds often contain numbers called subscripts - ex.) Na 3 P </li></ul><ul><li>If the metal forms only one type of ion, the subscript can be ignored when determining the name </li></ul>NAMING IONIC COMPOUNDS
  47. 47. <ul><li>Although ionic compounds are made of charged particles , the compound itself has no net charge </li></ul><ul><li>All ion charges of an ionic compound must add up to zero </li></ul>NAMING IONIC COMPOUNDS
  48. 48. <ul><li>The positive and negative charges in an ionic compound must be equal </li></ul>RULE:
  49. 49. <ul><li>Example Problem 1: </li></ul><ul><li>Write the name of the ionic compound ZnF 2 </li></ul><ul><li>Name the metal ion: Zn forms only one type of ion (Zn 2+ ), so the name is zinc </li></ul><ul><li>Name the non-metal ion: The atom is fluor ine so the ion is fluor ide </li></ul><ul><li>Combine the names: zinc fluoride </li></ul>NAMING IONIC COMPOUNDS
  50. 50. <ul><li>Example Problem 2: </li></ul><ul><li>Write the name of the ionic compound Ti I 4 </li></ul><ul><li>Identify the ions that form the compound: Ti 4+ and I - </li></ul><ul><li>Name the metal ion: the ion has a 4+ charge, so the name is titanium(IV) </li></ul><ul><li>Name the non-metal ion: the name of the atom is iod ine , so the ion is iod ide </li></ul><ul><li>Combine the names: titanium(IV) iodide </li></ul>NAMING IONIC COMPOUNDS
  51. 51. <ul><li>A polyatomic ion is a group of atoms, usually of different elements, that act as a single ion </li></ul><ul><li>ex.) one atom of sulphur and four atoms of oxygen form the polyatomic ion called sulphate , or SO 4 2- </li></ul>POLYATOMIC IONS
  52. 52. <ul><li>Similar polyatomic ions are named using the suffixes “ -ate ” or “ -ite ” </li></ul><ul><li>ex.) NO 3 - is nitrate; NO 2 - is nitrite </li></ul><ul><li>Most common polyatomic ions have a negative charge </li></ul><ul><li>However, the ammonium ion NH 4 + has a positive charge </li></ul>POLYATOMIC IONS
  53. 53. SO 3 2- sulphite SO 4 2- sulphate PO 3 3- phosphite PO 4 3- phosphate MnO 4 - permanganate NO 2 - nitrite NO 3 - nitrate OH - hydroxide HCO 3 - hydrogen carbonate (bicarbonate) CO 3 2- carbonate NH 4 + ammonium Formula Name
  54. 54. <ul><li>Example Problem 3: </li></ul><ul><li>Write the name of the ionic compound LiHCO 3 </li></ul><ul><li>Name the metal/positive ion: Li + = lithium </li></ul><ul><li>Identify the polyatomic ion (use table): HCO 3 - = hydrogen carbonate </li></ul><ul><li>Combine the names: lithium hydrogen carbonate </li></ul>NAMING IONIC COMPOUNDS

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