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Molecules and Compounds: Nomenclature

Molecules and Compounds: Nomenclature. Compounds vs. Elements. Compound 1: Table Salt Properties : Soluble crystals, stable, edible Elements (Components) Sodium – shiny, reactive, poisonous Chlorine – pale yellow gas, reactive, poisonous Compound 2: Table sugar

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Molecules and Compounds: Nomenclature

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  1. Molecules and Compounds: Nomenclature

  2. Compounds vs. Elements Compound 1: Table Salt Properties: Soluble crystals, stable, edible Elements (Components) • Sodium – shiny, reactive, poisonous • Chlorine – pale yellow gas, reactive, poisonous Compound 2: Table sugar Properties: sweet, soluble crystal Elements (Components) : • Carbon – pencil or diamonds • Hydrogen – flammable gas • Oxygen – a gas in air  Sugar:

  3. Law of Constant Composition Pure substances have constant composition • all samples of a pure substance contain the same elements in the same percentages (ratios): Water (H: 11%, O: 89%), Table salt (Na: 39%, Cl: 61%), Sugar • mixtures have variable composition: Air, Seawater, Concrete, Rocky road ice cream, Coke

  4. Why do Compounds ShowConstant Composition • the smallest piece of a compound is called a molecule: Water molecule, Sugar molecule • every molecule of a compound has the same number and type of atoms. Water molecule: 2 Hydrogen atom + 1 Oxygen atom; Sugar molecule: 12 Carbon atom + 22 Hydrogen atom + 11 Oxygen atom  every sample of the compound will have the same ratio of the elements

  5. Chemical Formula Chemical formula: describe the compound by describing the number and type of each atom in the simplest unit of the compound • molecules or ions (Table salt: Cl+, Na-) • Element represented by its letter symbol: H instead of hydrogen; Na instead of Sodium • #Atoms of each element: the right of the element as a subscript, H2O (unless if there is only one atom, the 1 subscript is not written) • Polyatomic groups (multiple atoms in group, example: CO3) are placed in parenthesesif more than one

  6. From Composition to Chemical Formula water = H2O \ two atoms of hydrogen and 1 atom of oxygen table sugar = C12H22O11\12 atoms of C, 22 atoms of H and 11 atoms O

  7. Classifying Pure Substances Element • Atomic: consists of single atoms (Metals, Noble gases) • Molecular: consists of multi-atom molecules (O2, N2, Cl2, etc) Compound • Molecular: consists of molecules made of only nonmetals (CO2, H2O) • Ionic: consists of cations (Na+) and anions (Cl-)

  8. Elements and Compounds

  9. Classify each of the following:Element atomic/molecularCompound  molecular/ionic • aluminum, Al • aluminum chloride, AlCl3 • chlorine, Cl2 • acetone, C3H6O • carbon monoxide, CO • cobalt, Co • aluminum, Al = atomic element • aluminum chloride, AlCl3= ionic compound • chlorine, Cl2= molecular element • acetone, C3H6O = molecular compound • carbon monoxide, CO = molecular compound • cobalt, Co = atomic element

  10. Molecular Elements Certain elements occur as 2 atom molecules • Rule of 7’s • there are 7 common diatomic elements • find the element with atomic number 7, N • make a figure 7 by going over to Group 7A, then down • don’t forget to include H2 VIIA 7 H2 N2 O2 F2 Cl2 Br2 I2

  11. Molecular Elements = Metal = Metalloid = Nonmetal H N O F Cl Br I

  12. Molecular Compounds • two or more nonmetals • smallest unit is a molecule • Common examples: H2O • CO2 (as in soda and dry ice) • NH3 (as in Windex), • Table sugar C11H22O11

  13. Ionic Compounds Ions: Metals (Cation Mx+) and Nonmetals (Anion Ny-) • No individual molecules!! • have a 3-dimensional array of cations and anions made of formula units: NaCl, MgO • Na+Cl-Na+Cl-Na+Cl- • Cl- Na+Cl-Na+Cl-Na+ • Na+Cl- Na+Cl-Na+Cl-

  14. Binary Molecular Compounds:Two Nonmetals (such as CO2) • Name first element in formula first • use the full name of the element • Name the second element in the formula with an -ide • as if it were an anion, however, remember these compounds do not contain ions! • Use a prefix in front of each name to indicate the number of atoms • Never use the prefix mono- on the first element

  15. Subscript - Prefixes • 5 = penta- • 6 = hexa- • 7 = hepta- • 8 = octa- • drop last “a” if name begins with vowel • 1 = mono-; • not used on first nonmetal • 2 = di- • 3 = tri- • 4 = tetra-

  16. Exceptions when Naming Molecular Compounds of course, water Other common exceptions: • NH3: ammonia (as in Windex) • H2S: hydrogen sulfide • HCl: hydrogen chloride (same for HX, where X = halogen) • CH4: methane (as in natural gas) • H2O2: hydrogen peroxide

  17. Example – Naming Binary MolecularBF3 • Is it one of the common exceptions? H2O, NH3, CH4, C12H22O11 = No! • Identify Major Class B = is a nonmetal because it is on the right side of the PT F = is a nonmetal because it is on the right side of the PT  Molecular • Identify the Subclass 2 elements  Binary Molecular

  18. Example – Naming Binary MolecularBF3 • Name the first element boron • Name the second element with an –ide fluorine  fluoride • Add a prefix to each name to indicate the subscript monoboron, trifluoride • Write the first element with prefix, then the second element with prefix • Drop prefix mono from first element boron trifluoride

  19. Practice: Naming Molecular Compounds • CO • ClO3 • SO2 • P2O5 • N2O4 • IF7 • SF6

  20. Key to Naming Molecular Compounds • COcarbon monoxide • ClO3 chlorine trioxide • SO2sulfur dioxide • P2O5 diphosphorus pentoxide • N2O4 dinitrogen tetroxide • IF7 iodine heptoxide • SF6 sulfur hexafluoride • CO • ClO3 • SO2 • P2O5 • N2O4 • IF7 • SF6

  21. Ionic Compounds • Made of Cation (+) and Anion (-) • Name: Cation Anion example: NaCl Sodium Chloride • Cation: • Type I metal • Type II metal • Polyatomic ion: ammonium NH4+ • Anion: • Nonmetal: Chloride Cl-, Oxide O2- • Polyatomic ion: SO42- , OH- , NO3-

  22. Metal Cations: Type I Type I (Groups IA, IIA, AZA) • only have one possible charge • Groups IA, IIA, Ag+, Zn2+, Al3+ • Charge by position on the Periodic Table • IA = +1, IIA = +2, • Ag+(IB), Zn2+(IIB) Al3+(IIIA) How do you know a metal cation is Type II? its not Type I !!!

  23. Metal Cations: Type II Type II: Metal ions that are other than Type I Common Examples: Fe2+/3+, Cu+/2+, Cr3+/6+, Mn2+/4+, Mn2+/4+, Pb2+/4+, Sn2+/4+, etc ) • have more than one possible charge • determine charge by charge on anion How do you know a metal cation is Type II? its not Type I !!!

  24. Metal Cations: Type I vs. Type II = Type I Metal = Type II Metal Al Zn Ag

  25. Monatomic Nonmetal Anion (An-) • How much is the charge? the position on the Periodic Table • Name of the anion: change ending on the element name to –ide

  26. Net charge of Ionic Compound = 0 • Net charge = Positive charge from cation(s) + Negative charge from Anion(s) = 0 • Example: Compound Al2(SO4)3, the Net charge = 2 x (+3) + 3 x (-2) = +6 - 6 = 0

  27. Name of Ionic Compounds • Name: Cation Anion: Sodium Chloride • Cation: • Type I metal = metal name : Na+ => Sodium, Mg2+ => Magnesium • Type II metal = metal name(charge): Fe3+Iron(III), Cu2+Copper(II) • Polyatomic ion = name of polyatomic ion, NH4+ => Ammonium • Anion: • Nonmetal = stem of nonmetal name + ide, Chloride, Oxide • Polyatomic ion = name of polyatomic ion, SO42- => Sulfate, OH- => Hydroxide, NO3- => Nitrate

  28. Type I Binary Ionic Compounds Binary: only two kinds of ions in one UNIT Example: MgO, CaCl2 • Metal listed first in formula & name • Metal Cation  Nonmetal Anion • Cation name <= Metal name: Magnesium, Calcium • Nonmetal anion <= Nonmetal name ends with –ide: Oxide, Chloride

  29. Example – Naming Binary Ionic, Type I MetalCsF • Is it one of the common exceptions? H2O, NH3, CH4, C12H22O11 No! • Identify Major Class Cs = is a metal because it is on the left side of the PT F = is a nonmetal because it is on the right side of the PT  Ionic • Identify the Subclass 2 elements,  Binary Ionic • Is the metal Type I or Type II Cs is in Group IA,  Type I

  30. Example – Naming Binary Ionic, Type I MetalCsF • Identify cation and anion Cs = Cs+ because it is Group 1 F = F- because it is Group 7 • Name the cation Cs+ = cesium • Name the anion F- = fluoride • Full name: Cation name first, Anion name last cesium fluoride

  31. Type II Binary Ionic Compounds Metal listed first in formula & name • Metal cation  Nonmetal anion • metal cation  Metal(Roman Numeral): to indicate its charge. Iron(II), Copper(I) • determine charge from anion charge • Common Type II cations in Table 5.5 • Nonmetal anion  Nonmetal name ended with –ide: Chloride, Oxide Example: Iron(II) chloride, Copper(I) oxide

  32. How to find the charge on Type II metal ions? • Example: Name Compound Fe2(SO4)3 Since the sum of all charges equals zero, the charge on iron ions are unknown and sulfate each has –2 charge, then we have 2 x Fe + 3 x (-2) = 0 Fe = +3, each iron ion has a charge of +3 Name: iron(III) sulfate Key: knowing the charge on ANIONs!

  33. Example – Naming Binary Ionic, Type II MetalCuCl • Is it one of the common exceptions? H2O, NH3, CH4, C12H22O11 = No! • Identify Major Class Cu = is a metal because it is on the left side of the PT Cl = is a nonmetal because it is on the right side of the PT  Ionic • Identify the Subclass 2 elements,  Binary Ionic • Is the metal Type I or Type II Cu is not in Group IA, IIA, or (Al, Ga, In)  Type II

  34. Example – Naming Binary Ionic, Type II MetalCuCl • Identify cation and anion Cl = Cl- because it is Group 7 Cu = Cu+ to balance the charge • Name the cation Cu+ = copper(I) • Name the anion Cl- = chloride • Write the cation name first, then the anion name copper(I) chloride

  35. Practice: Naming Ionic compounds • HgF2 • CuI2 • CaCl2 • Fe2O3 • SnCl4 • Mg3N2 • Ag2S

  36. Naming Ionic compounds Hints: find type II ion charge from anion • HgF2 : Two F- = -2 Hg = +2 • CuI2 : Two I- = -2 Cu = +2 • CaCl2 : both fixed charges • Fe2O3 : Three O2- = -6 Fe = +3 • SnBr4 : Four Br- = -4 Sn = +4 • Mg3N2 : both fixed charges • Ag2S : both fixed charges • HgF2 : Two F- = -2 • CuI2 : Two I- = -2 • CaCl2 : both fixed charges • Fe2O3 : Three O2- = -6 • SnBr4 : Four Br- = -4 • Mg3N2 : both fixed charges • Ag2S : both fixed charges

  37. Answer key: names of ionic compounds • HgF2 = Mercury(II) fluoride • CuI2 = copper(II) iodide • CaCl2 = calcium chloride • Fe2O3 = Iron(III) oxide • SnBr4 = tin(IV) bromide • Mg3N2 = magnesium nitride • Ag2S = silver sulfide

  38. symbol of the polyatomic ion called nitrate symbol of the polyatomic ion called sulfate implied “1” subscript on magnesium implied “1” subscript on calcium parentheses to group two NO3’s no parentheses for one SO4 Polyatomic Ions Mg(NO3)2 compound called magnesium nitrate CaSO4 compound called calcium sulfate

  39. subscript indicating two NO3 groups no subscript indicating one SO4 group implied “1” subscript on nitrogen, total 2 N implied “1” subscript on sulfur, total 1 S stated “4” subscript on oxygen, total 4 O stated “3” subscript on oxygen, total 6 O Polyatomic Ions:Nitrate NO3-, Sulfate SO42- Mg(NO3)2 compound called magnesium nitrate CaSO4 compound called calcium sulfate

  40. Polyatomic Anions: -ATE ions

  41. 3- 2- - BO CO NO 3 3 3 2- 3- 2- - SiO PO SO ClO 3 4 4 3 3- 2- - AsO SeO BrO 4 4 3 2- - TeO IO 4 3 Periodic Pattern of Polyatomic Ions-ate groups IIIA IVA VA VIA VIIA

  42. Patterns for Polyatomic Ions • elements in the same Group form similar polyatomic ions • same number of O’s and same charge ClO3-= chlorate (-1 charge) BrO3- = bromate (-1 charge) • if the polyatomic ion starts with H, the name adds hydrogen- prefix before name and add 1 to the charge CO32- = carbonate \ HCO3-1 = hydrogen carbonate

  43. Patterns for Polyatomic Ions -ate ion • chlorate = ClO3- • -ate ion + 1 O same charge, per- prefix • perchlorate = ClO4- • -ate ion – 1 O same charge, -ite suffix • chlorite = ClO2- • -ate ion – 2 O same charge, hypo- prefix, -ite suffix • hypochlorite = ClO-

  44. Polyatomic Anions: -ite, hypo- -ite, (-ate),per- -ate

  45. -ATE/-ITE ions in Our Lives

  46. Polyatomic Ions to Remember

  47. Other Polyatomic Ions in Our Lives

  48. Other Polyatomic Ions in Our Lives

  49. Compounds Containing Polyatomic Ions • Type I metal + Polyatomic ion: NaNO3 • Type II metal(charge) + Polyatomic ion : CuSO4 • Polyatomic cation + Nonmetal ion (-ide): NH4Cl • Polyatomic cation + Polyatomic ion: (NH4)2SO4 Important!: If, and only if, more than ONE polyatomic ions are present in a formula, use parenthesis and subscript to indicate the number of polyatomic ions

  50. Example – Naming Ionic with Polyatomic IonNa2SO4 • Is it one of the common exceptions? H2O, NH3, CH4, C12H22O11 = No! • Identify Major Class Na = is a metal because it is on the left side of the PT SO4 = is a polyatomic ion  Ionic • Identify the Subclass compound has 3 elements  Ionic with Polyatomic Ion • Is the metal Type I or Type II Na is in Group IA,  Type I

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